80 results on '"Joanna K Barstow"'
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2. The effect of stellar contamination on low-resolution transmission spectroscopy: needs identified by NASA’s Exoplanet Exploration Program Study Analysis Group 21
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Benjamin V Rackham, Néstor Espinoza, Svetlana V Berdyugina, Heidi Korhonen, Ryan J MacDonald, Benjamin T Montet, Brett M Morris, Mahmoudreza Oshagh, Alexander I Shapiro, Yvonne C Unruh, Elisa V Quintana, Robert T Zellem, Dániel Apai, Thomas Barclay, Joanna K Barstow, Giovanni Bruno, Ludmila Carone, Sarah L Casewell, Heather M Cegla, Serena Criscuoli, Catherine Fischer, Damien Fournier, Mark S Giampapa, Helen Giles, Aishwarya Iyer, Greg Kopp, Nadiia M Kostogryz, Natalie Krivova, Matthias Mallonn, Chima McGruder, Karan Molaverdikhani, Elisabeth R Newton, Mayukh Panja, Sarah Peacock, Kevin Reardon, Rachael M Roettenbacher, Gaetano Scandariato, Sami Solanki, Keivan G Stassun, Oskar Steiner, Kevin B Stevenson, Jeremy Tregloan-Reed, Adriana Valio, Sven Wedemeyer, Luis Welbanks, Jie Yu, Munazza K Alam, James R A Davenport, Drake Deming, Chuanfei Dong, Elsa Ducrot, Chloe Fisher, Emily Gilbert, Veselin Kostov, Mercedes López-Morales, Mike Line, Teo Močnik, Susan Mullally, Rishi R Paudel, Ignasi Ribas, and Jeff A Valenti
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- 2023
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3. A JWST NIRSpec Phase Curve for WASP-121b: Dayside Emission Strongest Eastward of the Substellar Point and Nightside Conditions Conducive to Cloud Formation
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Thomas Mikal-Evans, David K. Sing, Jiayin Dong, Daniel Foreman-Mackey, Tiffany Kataria, Joanna K. Barstow, Jayesh M. Goyal, Nikole K. Lewis, Joshua D. Lothringer, Nathan J. Mayne, Hannah R. Wakeford, Duncan A. Christie, and Zafar Rustamkulov
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Exoplanet astronomy ,Exoplanet atmospheres ,Astrophysics ,QB460-466 - Abstract
We present the first exoplanet phase-curve measurement made with the JWST NIRSpec instrument, highlighting the exceptional stability of this newly commissioned observatory for exoplanet climate studies. The target, WASP-121b, is an ultrahot Jupiter with an orbital period of 30.6 hr. We analyze two broadband light curves generated for the NRS1 and NRS2 detectors, covering wavelength ranges of 2.70–3.72 μ m and 3.82–5.15 μ m, respectively. Both light curves exhibit minimal systematics, with approximately linear drifts in the baseline flux level of 30 ppm hr ^−1 (NRS1) and 10 ppm hr ^−1 (NRS2). Assuming a simple brightness map for the planet described by a low-order spherical harmonic dipole, our light-curve fits suggest that the phase curve peaks coincide with orbital phases 3.°36 ± 0.°11 (NRS1) and 2.°66 ± 0.°12 (NRS2) prior to mideclipse. This is consistent with the strongest dayside emission emanating from eastward of the substellar point. We measure planet-to-star emission ratios of 3924 ± 7 ppm (NRS1) and 4924 ± 9 ppm (NRS2) for the dayside hemisphere and 136 ± 8 ppm (NRS1) and 630 ± 10 ppm (NRS2) for the nightside hemisphere. The latter nightside emission ratios translate to planetary brightness temperatures of 926 ± 12 K (NRS1) and 1122 ± 10 K (NRS2), which are low enough for a wide range of refractory condensates to form, including enstatite and forsterite. A nightside cloud deck may be blocking emission from deeper, hotter layers of the atmosphere, potentially helping to explain why cloud-free 3D general circulation model simulations systematically overpredict the nightside emission for WASP-121b.
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- 2023
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4. The Hubble PanCET Program: A Featureless Transmission Spectrum for WASP-29b and Evidence of Enhanced Atmospheric Metallicity on WASP-80b
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Ian Yu Wong, Yayaati Chachan, Heather Knutson, Gregory W Henry, Danica Adams, Tiffany Kataria, Bjorn Benneke, Peter Gao, Drake Deming, Mercedes Lopez-Morales, David K. Sing, Munazza K Alam, Gilda E Ballester, Joanna K Barstow, Lars Buchhave, Leonardo A. dos Santos, Guangwei Fu, Antonio Garcia Munoz, Ryan J MacDonald, Thomas Mikal-Evans, Jorge Sanz-Forcada, and Hannah R Wakeford
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Astronomy ,Astrophysics - Abstract
We present a uniform analysis of transit observations from the Hubble Space Telescope and Spitzer Space Telescope of two warm gas giants orbiting K-type stars—WASP-29b and WASP-80b. The transmission spectra, which span 0.4–5.0μm, are interpreted using a suite of chemical equilibrium PLATON atmospheric retrievals. Both planets show evidence of significant aerosol opacity along the day–night terminator. The spectrum of WASP-29b is flat throughout the visible and near-infrared, suggesting the presence of condensate clouds extending to low pressures. The lack of spectral features hinders our ability to constrain the atmospheric metallicity and C/O ratio. In contrast, WASP-80b shows a discernible, albeit muted H2O absorption feature at 1.4μm, as well as a steep optical spectral slope that is caused by fine-particle aerosols and/or contamination from unocculted spots on the variable host star. WASP-80b joins the small number of gas-giant exoplanets that show evidence for enhanced atmospheric metallicity: the transmission spectrum is consistent with metallicities ranging from∼30–100 times solar in the case of cloudy limbs to a few hundred times solar in the cloud-free scenario. In addition to the detection of water, we infer the presence of CO2in the atmosphere of WASP-80b based on the enhanced transit depth in the Spitzer 4.5μm bandpass. From a complementary analysis of Spitzer secondary eclipses, we find that the day side emission from WASP-29b and WASP-80b is consistent with brightness temperatures of 937±48 and 851±14 K, respectively, indicating relatively weak day–night heat transport and low Bond albedo.
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- 2022
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5. Abundance measurements of H2O and carbon-bearing species in the atmosphere of WASP-127b confirm its supersolar metallicity
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Jessica J Spake, David K Sing, Hannah R Wakeford, Nikolay Nikolov, Thomas Mikal-Evans, Drake Deming, Joanna K Barstow, David R Anderson, Aarynn L Carter, Michael Gillon, Jayesh M Goyal, Guillaume Hebrard, Coel Hellier, Tiffany Kataria, Kristine W F Lam, A H M J Triaud, and Peter J Wheatley
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- 2020
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6. A comparison of exoplanet spectroscopic retrieval tools
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Joanna K Barstow, Quentin Changeat, Ryan Garland, Michael R Line, Marco Rocchetto, and Ingo P Waldmann
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- 2020
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7. Early Release Science of the exoplanet WASP-39b with JWST NIRCam
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Eva-Maria Ahrer, Kevin B. Stevenson, Megan Mansfield, Sarah E. Moran, Jonathan Brande, Giuseppe Morello, Catriona A. Murray, Nikolay K. Nikolov, Dominique J. M. Petit dit de la Roche, Everett Schlawin, Peter J. Wheatley, Sebastian Zieba, Natasha E. Batalha, Mario Damiano, Jayesh M. Goyal, Monika Lendl, Joshua D. Lothringer, Sagnick Mukherjee, Kazumasa Ohno, Natalie M. Batalha, Matthew P. Battley, Jacob L. Bean, Thomas G. Beatty, Björn Benneke, Zachory K. Berta-Thompson, Aarynn L. Carter, Patricio E. Cubillos, Tansu Daylan, Néstor Espinoza, Peter Gao, Neale P. Gibson, Samuel Gill, Joseph Harrington, Renyu Hu, Laura Kreidberg, Nikole K. Lewis, Michael R. Line, Mercedes López-Morales, Vivien Parmentier, Diana K. Powell, David K. Sing, Shang-Min Tsai, Hannah R. Wakeford, Luis Welbanks, Munazza K. Alam, Lili Alderson, Natalie H. Allen, David R. Anderson, Joanna K. Barstow, Daniel Bayliss, Taylor J. Bell, Jasmina Blecic, Edward M. Bryant, Matthew R. Burleigh, Ludmila Carone, S. L. Casewell, Quentin Changeat, Katy L. Chubb, Ian J. M. Crossfield, Nicolas Crouzet, Leen Decin, Jean-Michel Désert, Adina D. Feinstein, Laura Flagg, Jonathan J. Fortney, John E. Gizis, Kevin Heng, Nicolas Iro, Eliza M.-R. Kempton, Sarah Kendrew, James Kirk, Heather A. Knutson, Thaddeus D. Komacek, Pierre-Olivier Lagage, Jérémy Leconte, Jacob Lustig-Yaeger, Ryan J. MacDonald, Luigi Mancini, E. M. May, N. J. Mayne, Yamila Miguel, Thomas Mikal-Evans, Karan Molaverdikhani, Enric Palle, Caroline Piaulet, Benjamin V. Rackham, Seth Redfield, Laura K. Rogers, Pierre-Alexis Roy, Zafar Rustamkulov, Evgenya L. Shkolnik, Kristin S. Sotzen, Jake Taylor, P. Tremblin, Gregory S. Tucker, Jake D. Turner, Miguel de Val-Borro, Olivia Venot, Xi Zhang, Ahrer, Eva-Maria [0000-0003-0973-8426], Stevenson, Kevin B. [0000-0002-7352-7941], Apollo - University of Cambridge Repository, University of St Andrews. School of Physics and Astronomy, and Stevenson, Kevin B [0000-0002-7352-7941]
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141 ,Extraterrestrial Environment ,639/33/445/862 ,FOS: Physical sciences ,Planets ,5109 Space Sciences ,140 ,Exobiology ,QB Astronomy ,Instrumentation and Methods for Astrophysics (astro-ph.IM) ,Solar and Stellar Astrophysics (astro-ph.SR) ,QB ,Earth and Planetary Astrophysics (astro-ph.EP) ,MCC ,Multidisciplinary ,Atmosphere ,Settore FIS/05 ,article ,Water ,DAS ,639/33/34/862 ,Oxygen ,Astrophysics - Solar and Stellar Astrophysics ,5101 Astronomical Sciences ,Astrophysics - Instrumentation and Methods for Astrophysics ,51 Physical Sciences ,Astrophysics - Earth and Planetary Astrophysics - Abstract
Measuring the metallicity and carbon-to-oxygen (C/O) ratio in exoplanet atmospheres is a fundamental step towards constraining the dominant chemical processes at work and, if in equilibrium, revealing planet formation histories. Transmission spectroscopy provides the necessary means by constraining the abundances of oxygen- and carbon-bearing species; however, this requires broad wavelength coverage, moderate spectral resolution, and high precision that, together, are not achievable with previous observatories. Now that JWST has commenced science operations, we are able to observe exoplanets at previously uncharted wavelengths and spectral resolutions. Here we report time-series observations of the transiting exoplanet WASP-39b using JWST's Near InfraRed Camera (NIRCam). The long-wavelength spectroscopic and short-wavelength photometric light curves span 2.0 - 4.0 $\mu$m, exhibit minimal systematics, and reveal well-defined molecular absorption features in the planet's spectrum. Specifically, we detect gaseous H$_2$O in the atmosphere and place an upper limit on the abundance of CH$_4$. The otherwise prominent CO$_2$ feature at 2.8 $\mu$m is largely masked by H$_2$O. The best-fit chemical equilibrium models favour an atmospheric metallicity of 1-100$\times$ solar (i.e., an enrichment of elements heavier than helium relative to the Sun) and a sub-stellar carbon-to-oxygen (C/O) ratio. The inferred high metallicity and low C/O ratio may indicate significant accretion of solid materials during planet formation or disequilibrium processes in the upper atmosphere., Comment: 35 pages, 13 figures, 3 tables, Nature, accepted
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- 2023
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8. Early Release Science of the exoplanet WASP-39b with JWST NIRISS
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Adina D. Feinstein, Michael Radica, Luis Welbanks, Catriona Anne Murray, Kazumasa Ohno, Louis-Philippe Coulombe, Néstor Espinoza, Jacob L. Bean, Johanna K. Teske, Björn Benneke, Michael R. Line, Zafar Rustamkulov, Arianna Saba, Angelos Tsiaras, Joanna K. Barstow, Jonathan J. Fortney, Peter Gao, Heather A. Knutson, Ryan J. MacDonald, Thomas Mikal-Evans, Benjamin V. Rackham, Jake Taylor, Vivien Parmentier, Natalie M. Batalha, Zachory K. Berta-Thompson, Aarynn L. Carter, Quentin Changeat, Leonardo A. dos Santos, Neale P. Gibson, Jayesh M. Goyal, Laura Kreidberg, Mercedes López-Morales, Joshua D. Lothringer, Yamila Miguel, Karan Molaverdikhani, Sarah E. Moran, Giuseppe Morello, Sagnick Mukherjee, David K. Sing, Kevin B. Stevenson, Hannah R. Wakeford, Eva-Maria Ahrer, Munazza K. Alam, Lili Alderson, Natalie H. Allen, Natasha E. Batalha, Taylor J. Bell, Jasmina Blecic, Jonathan Brande, Claudio Caceres, S. L. Casewell, Katy L. Chubb, Ian J. M. Crossfield, Nicolas Crouzet, Patricio E. Cubillos, Leen Decin, Jean-Michel Désert, Joseph Harrington, Kevin Heng, Thomas Henning, Nicolas Iro, Eliza M.-R. Kempton, Sarah Kendrew, James Kirk, Jessica Krick, Pierre-Olivier Lagage, Monika Lendl, Luigi Mancini, Megan Mansfield, E. M. May, N. J. Mayne, Nikolay K. Nikolov, Enric Palle, Dominique J. M. Petit dit de la Roche, Caroline Piaulet, Diana Powell, Seth Redfield, Laura K. Rogers, Michael T. Roman, Pierre-Alexis Roy, Matthew C. Nixon, Everett Schlawin, Xianyu Tan, P. Tremblin, Jake D. Turner, Olivia Venot, William C. Waalkes, Peter J. Wheatley, Xi Zhang, University of St Andrews. School of Physics and Astronomy, Feinstein, Adina D [0000-0002-9464-8101], Line, Michael R [0000-0001-6247-8323], Rustamkulov, Zafar [0000-0003-4408-0463], Apollo - University of Cambridge Repository, Feinstein, Adina D. [0000-0002-9464-8101], and Line, Michael R. [0000-0001-6247-8323]
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Extraterrestrial Environment ,639/33/445/862 ,FOS: Physical sciences ,610 Medicine & health ,5109 Space Sciences ,140 ,QB Astronomy ,Instrumentation and Methods for Astrophysics (astro-ph.IM) ,Solar and Stellar Astrophysics (astro-ph.SR) ,QC ,QB ,Earth and Planetary Astrophysics (astro-ph.EP) ,Multidisciplinary ,Settore FIS/05 ,Spectrum Analysis ,article ,Water ,639/33/34/862 ,3rd-DAS ,Oxygen ,QC Physics ,Astrophysics - Solar and Stellar Astrophysics ,MCP ,Potassium ,570 Life sciences ,biology ,Astrophysics - Instrumentation and Methods for Astrophysics ,51 Physical Sciences ,Astrophysics - Earth and Planetary Astrophysics - Abstract
Transmission spectroscopy provides insight into the atmospheric properties and consequently the formation history, physics, and chemistry of transiting exoplanets. However, obtaining precise inferences of atmospheric properties from transmission spectra requires simultaneously measuring the strength and shape of multiple spectral absorption features from a wide range of chemical species. This has been challenging given the precision and wavelength coverage of previous observatories. Here, we present the transmission spectrum of the Saturn-mass exoplanet WASP-39b obtained using the SOSS mode of the NIRISS instrument on the JWST. This spectrum spans $0.6 - 2.8 \mu$m in wavelength and reveals multiple water absorption bands, the potassium resonance doublet, as well as signatures of clouds. The precision and broad wavelength coverage of NIRISS-SOSS allows us to break model degeneracies between cloud properties and the atmospheric composition of WASP-39b, favoring a heavy element enhancement ("metallicity") of $\sim 10 - 30 \times$ the solar value, a sub-solar carbon-to-oxygen (C/O) ratio, and a solar-to-super-solar potassium-to-oxygen (K/O) ratio. The observations are best explained by wavelength-dependent, non-gray clouds with inhomogeneous coverage of the planet's terminator., Comment: 48 pages, 12 figures, 2 tables. Under review at Nature
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- 2023
9. Using VIRTIS on Venus Express to Constrain the Properties of the Giant Dark Cloud Observed in Images of Venus by IR2 on Akatsuki
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Kevin McGouldrick, Javier Peralta, Joanna K. Barstow, and Constantine C. C. Tsang
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- 2021
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10. DMPP-3: confirmation of short-period S-type planet(s) in a compact eccentric binary star system, and warnings about long-period RV planet detections
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Adam T Stevenson, Carole A Haswell, John R Barnes, Joanna K Barstow, and Zachary O B Ross
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Earth and Planetary Astrophysics (astro-ph.EP) ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics - Instrumentation and Methods for Astrophysics ,Instrumentation and Methods for Astrophysics (astro-ph.IM) ,Solar and Stellar Astrophysics (astro-ph.SR) ,Astrophysics - Earth and Planetary Astrophysics - Abstract
We present additional HARPS radial velocity observations of the highly eccentric ($e \sim 0.6$) binary system DMPP-3AB, which comprises a K0V primary and a low-mass companion at the hydrogen burning limit. The binary has a $507$ d orbital period and a $1.2$ au semi-major axis. The primary component harbours a known $2.2$ M$_{\oplus}$ planet, DMPP-3A b, with a $6.67$ day orbit. New HARPS measurements constrain periastron passage for the binary orbit and add further integrity to previously derived solutions for both companion and planet orbits. Gaia astrometry independently confirms the binary orbit, and establishes the inclination of the binary is $63.89 \pm 0.78 ^{\circ}$. We performed dynamical simulations which establish that the previously identified $\sim800$ d RV signal cannot be attributed to an orbiting body. The additional observations, a deviation from strict periodicity, and our new analyses of activity indicators suggest the $\sim800$ d signal is caused by stellar activity. We conclude that there may be long period planet 'detections' in other systems which are similar misinterpreted stellar activity artefacts. Without the unusual eccentric binary companion to the planet-hosting star we could have accepted the $\sim800$ d signal as a probable planet. Further monitoring of DMPP-3 will reveal which signatures can be used to most efficiently identify these imposters. We also report a threshold detection (0.2 per cent FAP) of a $\sim2.26$ d periodicity in the RVs, potentially attributed to an Earth-mass S-type planet interior to DMPP-3A b., Comment: 20 pages, 15 figures. Accepted for publication in MNRAS
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- 2023
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11. The Effect of Stellar Contamination on Low-resolution Transmission Spectroscopy: Needs Identified by NASA's Exoplanet Exploration Program Study Analysis Group 21
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Benjamin V Rackham, Néstor Espinoza, Svetlana V Berdyugina, Heidi Korhonen, Ryan J MacDonald, Benjamin T Montet, Brett M Morris, Mahmoudreza Oshagh, Alexander I Shapiro, Yvonne C Unruh, Elisa V Quintana, Robert T Zellem, Dániel Apai, Thomas Barclay, Joanna K Barstow, Giovanni Bruno, Ludmila Carone, Sarah L Casewell, Heather M Cegla, Serena Criscuoli, Catherine Fischer, Damien Fournier, Mark S Giampapa, Helen Giles, Aishwarya Iyer, Greg Kopp, Nadiia M Kostogryz, Natalie Krivova, Matthias Mallonn, Chima McGruder, Karan Molaverdikhani, Elisabeth R Newton, Mayukh Panja, Sarah Peacock, Kevin Reardon, Rachael M Roettenbacher, Gaetano Scandariato, Sami Solanki, Keivan G Stassun, Oskar Steiner, Kevin B Stevenson, Jeremy Tregloan-Reed, Adriana Valio, Sven Wedemeyer, Luis Welbanks, Jie Yu, Munazza K Alam, James R A Davenport, Drake Deming, Chuanfei Dong, Elsa Ducrot, Chloe Fisher, Emily Gilbert, Veselin Kostov, Mercedes López-Morales, Mike Line, Teo Močnik, Susan Mullally, Rishi R Paudel, Ignasi Ribas, and Jeff A Valenti
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Earth and Planetary Astrophysics (astro-ph.EP) ,Astrophysics - Solar and Stellar Astrophysics ,FOS: Physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics - Instrumentation and Methods for Astrophysics ,Instrumentation and Methods for Astrophysics (astro-ph.IM) ,Solar and Stellar Astrophysics (astro-ph.SR) ,Astrophysics::Galaxy Astrophysics ,Astrophysics - Earth and Planetary Astrophysics - Abstract
Study Analysis Group 21 (SAG21) of NASA's Exoplanet Exploration Program Analysis Group (ExoPAG) was organized to study the effect of stellar contamination on space-based transmission spectroscopy, a method for studying exoplanetary atmospheres by measuring the wavelength-dependent radius of a planet as it transits its star. Transmission spectroscopy relies on a precise understanding of the spectrum of the star being occulted. However, stars are not homogeneous, constant light sources but have temporally evolving photospheres and chromospheres with inhomogeneities like spots, faculae, plages, granules, and flares. This SAG brought together an interdisciplinary team of more than 100 scientists, with observers and theorists from the heliophysics, stellar astrophysics, planetary science, and exoplanetary atmosphere research communities, to study the current research needs that can be addressed in this context to make the most of transit studies from current NASA facilities like HST and JWST. The analysis produced 14 findings, which fall into three Science Themes encompassing (1) how the Sun is used as our best laboratory to calibrate our understanding of stellar heterogeneities ("The Sun as the Stellar Benchmark"), (2) how stars other than the Sun extend our knowledge of heterogeneities ("Surface Heterogeneities of Other Stars") and (3) how to incorporate information gathered for the Sun and other stars into transit studies ("Mapping Stellar Knowledge to Transit Studies"). In this invited review, we largely reproduce the final report of SAG21 as a contribution to the peer-reviewed literature., Invited review in press at RASTI. Based on the ExoPAG SAG21 report (arXiv:2201.09905v1) and refined via feedback from three reviewers. 75 pages, 30 figures, 5 tables
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- 2022
12. Diurnal variations in the stratosphere of the ultrahot giant exoplanet WASP-121b
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Thomas Mikal-Evans, David K. Sing, Joanna K. Barstow, Tiffany Kataria, Jayesh Goyal, Nikole Lewis, Jake Taylor, Nathan J. Mayne, Tansu Daylan, Hannah R. Wakeford, Mark S. Marley, and Jessica J. Spake
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Earth and Planetary Astrophysics (astro-ph.EP) ,Physics::Space Physics ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,Physics::Atmospheric and Oceanic Physics ,Astrophysics - Earth and Planetary Astrophysics ,Physics::Geophysics - Abstract
The temperature profile of a planetary atmosphere is a key diagnostic of radiative and dynamical processes governing the absorption, redistribution, and emission of energy. Observations have revealed dayside stratospheres that either cool or warm with altitude for a small number of gas giant exoplanets, while other dayside stratospheres are consistent with constant temperatures. Here we report spectroscopic phase curve measurements for the gas giant WASP-121b, which constrain stratospheric temperatures throughout the diurnal cycle. Variations measured for a water vapour spectral feature reveal a temperature profile that transitions from warming with altitude on the dayside hemisphere to cooling with altitude on the nightside hemisphere. The data are well explained by models assuming chemical equilibrium, with water molecules thermally dissociating at low pressures on the dayside and recombining on the nightside. Nightside temperatures are low enough for perovskite (CaTiO3) to condense, which could deplete titanium from the gas phase and explain recent non-detections at the day-night terminator. Nightside temperatures are also consistent with the condensation of refractory species such as magnesium, iron, and vanadium. Detections of these metals at the day-night terminator suggest, however, that if they do form nightside clouds, cold trapping does not efficiently remove them from the upper atmosphere. Horizontal winds and vertical mixing could keep these refractory condensates aloft in the upper atmosphere of the nightside hemisphere until they are recirculated to the hotter dayside hemisphere and vaporised., Comment: Published in Nature Astronomy (publisher version is Open Access)
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- 2022
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13. Diurnal variations in the stratosphere of an ultrahot exoplanet
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David K. Sing, Mark S. Marley, Tansu Daylan, Jake Taylor, Nikole K. Lewis, Jayesh M. Goyal, Jessica Spake, Hannah R. Wakeford, Nathan J. Mayne, Thomas Mikal-Evans, Tiffany Kataria, and Joanna K. Barstow
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Environmental science ,Stratosphere ,Exoplanet ,Astrobiology - Abstract
The temperature profile of a planetary atmosphere is a key diagnostic of radiative and dynamical processes governing the absorption, redistribution, and emission of energy. Observations have revealed dayside stratospheres that either cool [1,2] or warm [3,4] with altitude for a small number of gas giant exoplanets, while others are consistent with constant temperatures [5,6,7,8]. Here we report spectroscopic phase curve measurements for the gas giant WASP-121b,[9] which constrain stratospheric temperatures throughout the diurnal cycle. Variations measured for a water vapor spectral feature reveal a temperature profile that transitions from warming with altitude on the dayside hemisphere to cooling with altitude on the nightside hemisphere. The data are well explained by models assuming chemical equilibrium, with water molecules thermally dissociating at low pressures on the dayside and recombining on the nightside [10,11]. Nightside temperatures are low enough for perovskite (CaTiO3) to condense, which could deplete titanium from the gas phase [12,13] and explain recent non-detections at the day-night terminator [14,15,16,17]. Nightside temperatures are also low enough for refractory species, such as magnesium, iron, and vanadium, to condense. Detections [16,17,18,19] of these metals at the day-night terminator suggest, however, that if they do form nightside clouds, cold trapping is not as effective at removing them from the upper atmosphere. Note: Numbered references have been entered into the "Manuscript Comment" box.
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- 2021
14. The search for living worlds and the connection to our cosmic origins
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C. Charbonnel, Christian Knigge, Monica Tosi, Joanna K. Barstow, Chris Evans, Chris Lintott, Maurizio Ferrari, A. Z. Bonanos, Eline Tolstoy, N. Devaney, Beth Biller, Miriam Garcia, Martin A. Barstow, Th. Henning, Suzanne Aigrain, Daphne Stam, Mathieu Barthelemy, Roger L. Davies, Sarah L. Casewell, Colin Snodgrass, Coralie Neiner, Loïc Rossi, Luca Fossati, Boris T. Gänsicke, A. I. Gómez de Castro, Lars A. Buchhave, Stéphane Charlot, School of Physics and Astronomy [Leicester], University of Leicester, Department of Physics [Oxford], University of Oxford [Oxford], School of Physical Sciences [Milton Keynes], Faculty of Science, Technology, Engineering and Mathematics [Milton Keynes], The Open University [Milton Keynes] (OU)-The Open University [Milton Keynes] (OU), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Institute for Astronomy [Edinburgh] (IfA), University of Edinburgh, National Observatory of Athens (NOA), National Space Institute [Lyngby] (DTU Space), Technical University of Denmark [Lyngby] (DTU), Observatoire Astronomique de l'Université de Genève (ObsGE), Université de Genève (UNIGE), Institut d'Astrophysique de Paris (IAP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), School of Physics [NUI Galway], National University of Ireland [Galway] (NUI Galway), UK Astronomy Technology Centre (UK ATC), Science and Technology Facilities Council (STFC), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Space Research Institute of Austrian Academy of Sciences (IWF), Austrian Academy of Sciences (OeAW), Department of Physics, University of Warwick, University of Warwick [Coventry], Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Departamento Fisica de la Tierra, Astronomía y Astrofísica [Madrid], Universidad Complutense de Madrid = Complutense University of Madrid [Madrid] (UCM), Max-Planck-Institut für Astronomie (MPIA), Max-Planck-Gesellschaft, School of Physics and Astronomy [Southampton], University of Southampton, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Delft University of Technology (TU Delft), Kapteyn Astronomical Institute [Groningen], University of Groningen [Groningen], INAF - Osservatorio Astronomico di Bologna (OABO), Istituto Nazionale di Astrofisica (INAF), Department of Physics and Astronomy [Leicester], School of Physics, University of Exeter, Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Sonnensystemforschung (MPS), SRON Netherlands Institute for Space Research (SRON), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), University of Oxford, Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France, Danmarks Tekniske Universitet = Technical University of Denmark (DTU), Université de Genève = University of Geneva (UNIGE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Neiner, Coralie, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), and Astronomy
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Solar System ,010504 meteorology & atmospheric sciences ,Computer science ,FOS: Physical sciences ,Astrophysics::Cosmology and Extragalactic Astrophysics ,[SDU.ASTR] Sciences of the Universe [physics]/Astrophysics [astro-ph] ,7. Clean energy ,01 natural sciences ,Space exploration ,Astrobiology ,law.invention ,Imaging ,Telescope ,[SDU] Sciences of the Universe [physics] ,[SDU.ASTR.IM] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM] ,Spitzer Space Telescope ,Planet ,law ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,Transit (astronomy) ,Stellar populations ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,Spectroscopy ,0105 earth and related environmental sciences ,QB ,Ultraviolet ,Earth and Planetary Astrophysics (astro-ph.EP) ,[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph] ,Exoplanets ,Astrophysics::Instrumentation and Methods for Astrophysics ,Astronomy and Astrophysics ,Stars ,Exoplanet ,[SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM] ,13. Climate action ,Space and Planetary Science ,[SDU]Sciences of the Universe [physics] ,Physics::Space Physics ,Astrophysics::Earth and Planetary Astrophysics ,Circumstellar habitable zone ,Astrophysics - Earth and Planetary Astrophysics - Abstract
One of the most exciting scientific challenges is to detect Earth-like planets in the habitable zones of other stars in the galaxy and search for evidence of life. The ability to observe and characterise dozens of potentially Earth-like planets now lies within the realm of possibility due to rapid advances in key space and imaging technologies. The associated challenge of directly imaging very faint planets in orbit around nearby very bright stars is now well understood, with the key instrumentation also being perfected and developed. Such advances will allow us to develop large transformative telescopes, covering a broad UV-optical-IR spectral range, which can carry out the detailed research programmes designed to answer the questions we wish to answer: Carry out high contrast imaging surveys of nearby stars to search for planets within their habitable zones. Characterise the planets detected to determine masses and radii from photometric measurements. Through spectroscopic studies of their atmospheres and surfaces, search for habitability indicators and for signs of an environment that has been modified by the presence of life. Active studies of potential missions have been underway for a number of years. The latest of these is the Large UV Optical IR space telescope (LUVOIR), one of four flagship mission studies commissioned by NASA in support of the 2020 US Decadal Survey. LUVOIR, if selected, will be of interest to a wide scientific community and will be the only telescope capable of searching for and characterizing a sufficient number of exoEarths to provide a meaningful answer to the question - Are we alone?. This paper is a submission to the European Space Agency Voyage 2050 call for white papers outlining the case for an ESA contribution to a Large UVOIR telescope., Submission to the European Space Agency Voyage 2050 call for white papers
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- 2021
15. Atmospheric Modeling and Retrieval
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Joanna K. Barstow, Jonathan J. Fortney, and Nikku Madhusudhan
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Meteorology ,Environmental science ,Atmospheric model - Published
- 2021
16. Using VIRTIS on Venus Express to Constrain the Properties of the Giant Dark Cloud Observed in Images of Venus by IR2 on Akatsuki
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Joanna K. Barstow, Kevin McGouldrick, Constantine Tsang, Javier Peralta, Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear, and National Aeronautics and Space Administration. US
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biology ,Opacity ,Baroclinity ,Astronomy ,Astronomy and Astrophysics ,Venus ,biology.organism_classification ,Latitude ,Atmosphere of Venus ,Geophysics ,Altitude ,Space and Planetary Science ,Cloud base ,Earth and Planetary Sciences (miscellaneous) ,Geology ,Water vapor - Abstract
A cloud opacity contrast feature that has been called a “long-lived sharp disruption” has been seen in the atmosphere of Venus in the near-infrared using Akatsuki’s IR2 camera, most clearly at equatorial latitudes. This feature was found to have a consistent planet-circling period of 4.9 days, and subsequent searches of past imagery revealed that it has probably existed for at least 30 years, the duration of near-infrared investigation of the deep atmosphere of Venus. Guided by the remarkably consistent morphological appearance of this feature, we have identified at least one previous instance of it in the Venus Express Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) data. We take advantage of the spectroscopic capabilities of VIRTIS to retrieve atmospheric parameters in the vicinity of this feature that cannot be retrieved using the limited filter selection on board Akatsuki. We find that the changes in measurable quantities, such as cloud particle acid mass fraction, water vapor, carbon monoxide, cloud base altitude, and particle size, suggest that the changes that take place in the vicinity of this feature are restricted to the lower clouds of Venus (below 50 km). We hypothesize that further evolution of this feature (over timescales of days to weeks) results in measurable variations in these parameters at altitudes in the middle clouds of Venus (50–57 km), lending credence to its identification as a baroclinic trough or Kelvin front.
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- 2021
17. The ExoMolOP database : cross sections and k-tables for molecules of interest in high-temperature exoplanet atmospheres
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Michiel Min, Mark W. Phillips, Ingo Waldmann, Ahmed Al-Refaie, Katy L. Chubb, Jonathan Tennyson, Paul Mollière, Marco Rocchetto, Sergei N. Yurchenko, Joanna K. Barstow, and University of St Andrews. School of Physics and Astronomy
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Opacity ,010504 meteorology & atmospheric sciences ,FOS: Physical sciences ,Astrophysics ,planetary systems [Infrared] ,computer.software_genre ,01 natural sciences ,Resonance (particle physics) ,Atmosphere ,0103 physical sciences ,Radiative transfer ,Molecule ,QB Astronomy ,Instrumentation and Methods for Astrophysics (astro-ph.IM) ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,QC ,0105 earth and related environmental sciences ,Line (formation) ,QB ,Earth and Planetary Astrophysics (astro-ph.EP) ,Physics ,Database ,Molecular data ,Astronomy and Astrophysics ,3rd-DAS ,Exoplanet ,gaseous planets [Planets and satellites] ,QC Physics ,Astrophysics - Solar and Stellar Astrophysics ,13. Climate action ,Space and Planetary Science ,atmospheres [Planets and satellites] ,Astrophysics::Earth and Planetary Astrophysics ,HITRAN ,Astrophysics - Instrumentation and Methods for Astrophysics ,computer ,Astrophysics - Earth and Planetary Astrophysics - Abstract
A publicly available database of opacities for molecules of astrophysical interest, ExoMolOP, has been compiled for over 80 species, based on the latest line list data from the ExoMol, HITEMP and MoLLIST databases. These data are generally suitable for characterising high temperature exoplanet or cool stellar/substellar atmospheres, and have been computed at a variety of pressures and temperatures, with a few molecules included at room-temperature only from the HITRAN database. The data are formatted in different ways for four different exoplanet atmosphere retrieval codes; ARCiS, TauREx, NEMESIS and petitRADTRANS, and include both cross-sections (at R~=~$\frac{\lambda}{\Delta \lambda}$~=~15,000) and k-tables (at R~=~$\frac{\lambda}{\Delta \lambda}$~=~1000) for the 0.3~-~50$\mu$m wavelength region. Opacity files can be downloaded and used directly for these codes. Atomic data for alkali metals Na and K are also included, using data from the NIST database and the latest line shapes for the resonance lines. Broadening parameters have been taken from the literature where available, or from those for a known molecule with similar molecular properties where no broadening data are available. The data are available from www.exomol.com., Comment: 25 pages, 9 figures. Accepted for publication in A&A
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- 2021
18. HST PanCET Program: A Complete Near-UV to Infrared Transmission Spectrum for the Hot Jupiter WASP-79b
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Lars A. Buchhave, Jorge Sanz-Forcada, Munazza K. Alam, Jayesh M. Goyal, Joanna K. Barstow, David K. Sing, João M. Mendonça, Nikolay Nikolov, Katy L. Chubb, Alexander D. Rathcke, Jake Taylor, Mercedes Lopez-Morales, Gregory W. Henry, Nikole K. Lewis, Ryan J. MacDonald, University of St Andrews. School of Physics and Astronomy, Rathcke, A. D. [0000-0002-4227-4953], MacDonald, R. J. [0000-0003-4816-3469], Barstow, J. K. [0000-0003-3726-5419], Goyal, J. M. [0000-0002-8515-7204], López Morales, M. [0000-0003-3204-8183], Mendoça, J. M. [0000-0002-6907-4476], Sanz Forcada, J. [0000-0002-1600-7835], Henry, G. W. [0000-0003-4155-8513], Sing, D. K. [0000-0001-6050-7645], Alam, M. K. [0000-0003-4157-832X], Lewis, N. K. [0000-0002-8507-1304], Chubb, K. L. [0000-0002-4552-4559], Taylor, J. [0000-0003-4844-9838], Nikolov, N. [0000-0002-6500-3574], Buchhave, L. A. [0000-0003-1605-5666], and Agencia Estatal de Investigación (AEI)
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Opacity ,Metallicity ,Hot Jupiters ,NDAS ,FOS: Physical sciences ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Neptune-mass exoplanet ,Absorption ,Atmosphere ,Observational astronomy ,Hot Jupiter ,Transmission spectroscopy ,Giant planets ,QB Astronomy ,Astrophysics::Solar and Stellar Astrophysics ,Transit (astronomy) ,Gaussian process framework ,Spectroscopy ,QC ,Astrophysics::Galaxy Astrophysics ,QB ,Physics ,Earth and Planetary Astrophysics (astro-ph.EP) ,Photosphere ,Retrieval ,James Webb Space Telescope ,Astronomy and Astrophysics ,QC Physics ,Space and Planetary Science ,HD 189733B ,Exoplanets atmospheric composition ,Molecular line lists ,Astrophysics::Earth and Planetary Astrophysics ,Hubble ,Exoplanet atmospheres ,Astrophysics - Earth and Planetary Astrophysics - Abstract
We present a new optical transmission spectrum of the hot Jupiter WASP-79b. We observed three transits with the STIS instrument mounted on HST, spanning 0.3 - 1.0 um. Combining these transits with previous observations, we construct a complete 0.3 - 5.0 um transmission spectrum of WASP-79b. Both HST and ground-based observations show decreasing transit depths towards blue wavelengths, contrary to expectations from Rayleigh scattering or hazes. We infer atmospheric and stellar properties from the full near-UV to infrared transmission spectrum of WASP-79b using three independent retrieval codes, all of which yield consistent results. Our retrievals confirm previous detections of H$_{2}$O (at 4.0$\sigma$ confidence), while providing moderate evidence of H$^{-}$ bound-free opacity (3.3$\sigma$) and strong evidence of stellar contamination from unocculted faculae (4.7$\sigma$). The retrieved H$_{2}$O abundance ($\sim$ 1$\%$) suggests a super-stellar atmospheric metallicity, though stellar or sub-stellar abundances remain consistent with present observations (O/H = 0.3 - 34$\times$ stellar). All three retrieval codes obtain a precise H$^{-}$ abundance constraint: log(X$_{\rm{H^{-}}}$) $\approx$ -8.0 $\pm$ 0.7. The potential presence of H$^{-}$ suggests that JWST observations may be sensitive to ionic chemistry in the atmosphere of WASP-79b. The inferred faculae are $\sim$ 500 K hotter than the stellar photosphere, covering $\sim$ 15$\%$ of the stellar surface. Our analysis underscores the importance of observing UV - optical transmission spectra in order to disentangle the influence of unocculted stellar heterogeneities from planetary transmission spectra., Comment: 27 pages, 10 figures. Resubmitted to AJ after referee report
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- 2021
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19. Abundance measurements of H2O and carbon-bearing species in the atmosphere of WASP-127b confirm its super-solar metallicity
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K. W. F. Lam, David R. Anderson, Drake Deming, Michaël Gillon, N. Nikolov, Jayesh M. Goyal, Joanna K. Barstow, Amaury H. M. J. Triaud, Hannah R. Wakeford, David K. Sing, Aarynn L. Carter, Tiffany Kataria, Coel Hellier, Peter J. Wheatley, Guillaume Hébrard, Jessica Spake, and Thomas Mikal-Evans
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Physics ,010504 meteorology & atmospheric sciences ,Scattering ,Metallicity ,Astronomy and Astrophysics ,Astrophysics ,01 natural sciences ,Exoplanet ,Atmosphere ,Stars ,Space and Planetary Science ,Abundance (ecology) ,Planet ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,Spectroscopy ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,0105 earth and related environmental sciences ,QB799 - Abstract
The chemical abundances of exoplanet atmospheres may provide valuable information about the bulk compositions, formation pathways, and evolutionary histories of planets. Exoplanets with large, relatively cloud-free atmospheres, and which orbit bright stars provide the best opportunities for accurate abundance measurements. For this reason, we measured the transmission spectrum of the bright (V ∼ 10.2), large (1.37 RJ), sub-Saturn mass (0.19 MJ) exoplanet WASP-127b across the near-UV to near-infrared wavelength range (0.3–5 μm), using the Hubble and Spitzer Space Telescopes. Our results show a feature-rich transmission spectrum, with absorption from Na, H2O, and CO2, and wavelength-dependent scattering from small-particle condensates. We ran two types of atmospheric retrieval models: one enforcing chemical equilibrium, and the other which fit the abundances freely. Our retrieved abundances at chemical equilibrium for Na, O, and C are all supersolar, with abundances relative to solar values of 9$^{+15}_{-6}$, 16$^{+7}_{-5}$, and 26$^{+12}_{-9}$, respectively. Despite giving conflicting C/O ratios, both retrievals gave supersolar CO2 volume mixing ratios, which adds to the likelihood that WASP-127b’s bulk metallicity is supersolar, since CO2 abundance is highly sensitive to atmospheric metallicity. We detect water at a significance of 13.7σ. Our detection of Na is in agreement with previous ground-based detections, though we find a much lower abundance, and we also do not find evidence for Li or K despite increased sensitivity. In the future, spectroscopy with James Webb Space Telescope will be able to constrain WASP-127b’s C/O ratio, and may reveal the formation history of this metal-enriched, highly observable exoplanet.
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- 2021
20. Evidence of a Clear Atmosphere for WASP-62b: the Only Known Transiting Gas Giant in the JWST Continuous Viewing Zone
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Drake Deming, Munazza K. Alam, Nikole K. Lewis, Ryan J. MacDonald, Mercedes Lopez-Morales, David K. Sing, Joanna K. Barstow, James Kirk, Hannah R. Wakeford, Jorge Sanz-Forcada, Jayesh M. Goyal, Lars A. Buchhave, Alexander D. Rathcke, Thomas Mikal-Evans, Nikolay Nikolov, Alam, M. K. [0000-0003-4157-832X], López Morales, M. [0000-0003-3204-8183], MacDonald, R. J. [0000-0003-4816-3469], Nikolov, N. [0000-0002-6500-3574], Kirk, J. [0000-0002-4207-6615], Goyal, J. M. [0000-0002-8515-7204], Sing, D. K. [0000-0001-6050-7645], Wakeford, H. R. [0000-0003-4328-3867], Rathcke, A. D. [0000-0002-4227-4953], Deming, D. L. [0000-0001-5727-4094], Sanz Forcada, J. [0000-0002-1600-7835], Lewis, N. K. [0000-0002-8507-1304], Barstow, J. K. [0000-0003-3726-5419], Mikal Evans, T. [0000-0001-5442-1300], Buchhave, L. A. [0000-0003-1605-5666], National Aeronautics and Space Administration (NASA), National Science Foundation (NSF), and Agencia Estatal de Investigación (AEI)
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010504 meteorology & atmospheric sciences ,Infrared ,Gas giant ,FOS: Physical sciences ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Atmosphere ,0103 physical sciences ,Hot Jupiter ,Astrophysics::Solar and Stellar Astrophysics ,Emission spectrum ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,0105 earth and related environmental sciences ,Physics ,Earth and Planetary Astrophysics (astro-ph.EP) ,James Webb Space Telescope ,Giant planet ,Astrophysics::Instrumentation and Methods for Astrophysics ,Astronomy ,Astronomy and Astrophysics ,Exoplanet ,Exoplanets atmospheres ,Exoplanet atmospheric composition ,Space and Planetary Science ,Astrophysics::Earth and Planetary Astrophysics ,Planetary atmospheres ,Astrophysics - Earth and Planetary Astrophysics - Abstract
Exoplanets with cloud-free, haze-free atmospheres at the pressures probed by transmission spectroscopy represent a valuable opportunity for detailed atmospheric characterization and precise chemical abundance constraints. We present the first optical to infrared (0.3-5 microns) transmission spectrum of the hot Jupiter WASP-62b, measured with Hubble/STIS and Spitzer/IRAC. The spectrum is characterized by a 5.1-sigma detection of Na I absorption at 0.59 microns, in which the pressure-broadened wings of the Na D-lines are observed from space for the first time. A spectral feature at 0.4 microns is tentatively attributed to SiH at 2.1-sigma confidence. Our retrieval analyses are consistent with a cloud-free atmosphere without significant contamination from stellar heterogeneities. We simulate James Webb Space Telescope (JWST) observations, for a combination of instrument modes, to assess the atmospheric characterization potential of WASP-62b. We demonstrate that JWST can conclusively detect Na, H2O, FeH, and SiH within the scope of its Early Release Science (ERS) program. As the only transiting giant planet currently known in the JWST Continuous Viewing Zone, WASP-62b could prove a benchmark giant exoplanet for detailed atmospheric characterization in the James Webb era., 14 pages, 5 figures, accepted for publication in ApJL
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- 2020
21. Outstanding Challenges of Exoplanet Atmospheric Retrievals
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Joanna K. Barstow and Kevin Heng
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Solar System ,010504 meteorology & atmospheric sciences ,Computer science ,530 Physics ,FOS: Physical sciences ,01 natural sciences ,Planet ,0103 physical sciences ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,0105 earth and related environmental sciences ,Remote sensing ,Earth and Planetary Astrophysics (astro-ph.EP) ,520 Astronomy ,Astronomy and Astrophysics ,Inversion (meteorology) ,Phase curve ,500 Science ,Exoplanet ,Planetary science ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Atmospheric chemistry ,Spatial variability ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics - Earth and Planetary Astrophysics - Abstract
Spectral retrieval has long been a powerful tool for interpreting planetary remote sensing observations. Flexible, parameterised, agnostic models are coupled with inversion algorithms in order to infer atmospheric properties directly from observations, with minimal reliance on physical assumptions. This approach, originally developed for application to Earth satellite data and subsequently observations of other Solar System planets, has been recently and successfully applied to transit, eclipse and phase curve spectra of transiting exoplanets. In this review, we present the current state-of-the-art in terms of our ability to accurately retrieve information about atmospheric chemistry, temperature, clouds and spatial variability; we discuss the limitations of this, both in the available data and modelling strategies used; and we recommend approaches for future improvement., 30 pages, 6 figures. Accepted by Space Science Reviews
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- 2020
22. Ground-Based Transmission Spectroscopy with FORS2: A featureless optical transmission spectrum and detection of H$_2$O for the ultra-hot Jupiter WASP-103b
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David K. Sing, Savvas Constantinou, Nathan J. Mayne, Ernst J. W. de Mooij, Joanna K. Barstow, Thomas Mikal-Evans, Jamie Wilson, Nikku Madhusudhan, N. Nikolov, Christiane Helling, Neale P. Gibson, Benjamin Drummond, Jayesh M. Goyal, Aarynn L. Carter, University of St Andrews. School of Computer Science, University of St Andrews. School of Physics and Astronomy, and University of St Andrews. St Andrews Centre for Exoplanet Science
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stars: individual (WASP-103) ,FOS: Physical sciences ,Astrophysics ,individual (WASP-103) [stars] ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Spectral line ,symbols.namesake ,Hot Jupiter ,data analysis [methods] ,QB Astronomy ,Rayleigh scattering ,planetary systems ,QC ,Astrophysics::Galaxy Astrophysics ,QB ,Physics ,Earth and Planetary Astrophysics (astro-ph.EP) ,Very Large Telescope ,Scale height ,DAS ,Astronomy and Astrophysics ,Light curve ,methods: data analysis ,Exoplanet ,Wavelength ,QC Physics ,Space and Planetary Science ,symbols ,spectroscopic [techniques] ,Astrophysics::Earth and Planetary Astrophysics ,techniques: spectroscopic ,Astrophysics - Earth and Planetary Astrophysics - Abstract
We report ground-based transmission spectroscopy of the highly irradiated and ultra-short period hot-Jupiter WASP-103b covering the wavelength range $\approx$ 400-600 nm using the FORS2 instrument on the Very Large Telescope. The light curves show significant time-correlated noise which is mainly invariant in wavelength and which we model using a Gaussian process. The precision of our transmission spectrum is improved by applying a common-mode correction derived from the white light curve, reaching typical uncertainties in transit depth of $\approx$ 2x10$^{-4}$ in wavelength bins of 15 nm. After correction for flux contamination from a blended companion star, our observations reveal a featureless spectrum across the full range of the FORS2 observations and we are unable to confirm the Na absorption previously inferred using Gemini/GMOS or the strong Rayleigh scattering observed using broad-band light curves. We performed a Bayesian atmospheric retrieval on the full optical-infrared transmission spectrum using the additional data from Gemini/GMOS, HST/WFC3 and Spitzer observations and recover evidence for H$_2$O absorption at the 4.0$\sigma$ level. However, our observations are not able to completely rule out the presence of Na, which is found at 2.0$\sigma$ in our retrievals. This may in part be explained by patchy/inhomogeneous clouds or hazes damping any absorption features in our FORS2 spectrum, but an inherently small scale height also makes this feature challenging to probe from the ground. Our results nonetheless demonstrate the continuing potential of ground-based observations for investigating exoplanet atmospheres and emphasise the need for the application of consistent and robust statistical techniques to low-resolution spectra in the presence of instrumental systematics., Comment: 17 pages, 8 Figures, Accepted for publication in MNRAS
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- 2020
23. Detection of Na, K, and H2O in the hazy atmosphere of WASP-6b
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David K. Sing, Aarynn L. Carter, Joanna K. Barstow, Hannah R. Wakeford, Paul Wilson, Mercedes López-Morales, Munazza K. Alam, Antonio García Muñoz, Thomas Mikal-Evans, Gregory W. Henry, Sam Morrell, Nikolay Nikolov, Barry Smalley, Neale P. Gibson, Panayotis Lavvas, Jayesh M. Goyal, Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University [Cambridge]-Smithsonian Institution, Groupe de spectrométrie moléculaire et atmosphérique (GSMA), Université de Reims Champagne-Ardenne (URCA)-Centre National de la Recherche Scientifique (CNRS), Department of Physics and Astronomy, University College London, University College of London [London] (UCL), Zentrum für Astronomie und Astrophysik [Berlin] (ZAA), Technische Universität Berlin (TU), Astrophysics Research Centre [Belfast] (ARC), Queen's University [Belfast] (QUB), Department of Physics, University of Warwick, University of Warwick [Coventry], University of Exeter, Johns Hopkins University (JHU), Carl Sagan Institute, Cornell University [New York], MIT Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology (MIT), Space Telescope Science Institute (STSci), Smithsonian Institution-Harvard University [Cambridge], and Keele University [Keele]
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Haze ,010504 meteorology & atmospheric sciences ,planets and satellites ,photometrictechniques ,FOS: Physical sciences ,Astrophysics ,composition -planets and satellites ,Astrophysics::Cosmology and Extragalactic Astrophysics ,spectroscopic ,atmospheres -planets and satellites ,01 natural sciences ,0103 physical sciences ,Hot Jupiter ,QB460 ,Astrophysics::Solar and Stellar Astrophysics ,010303 astronomy & astrophysics ,Spectrograph ,Space Telescope Imaging Spectrograph ,QC ,gaseous planets -stars ,ComputingMilieux_MISCELLANEOUS ,Astrophysics::Galaxy Astrophysics ,0105 earth and related environmental sciences ,QB ,Physics ,Earth and Planetary Astrophysics (astro-ph.EP) ,Very Large Telescope ,James Webb Space Telescope ,Astrophysics::Instrumentation and Methods for Astrophysics ,Astronomy and Astrophysics ,Exoplanet ,13. Climate action ,Space and Planetary Science ,[SDU]Sciences of the Universe [physics] ,activity -techniques ,Astrophysics::Earth and Planetary Astrophysics ,Wide Field Camera 3 ,Astrophysics - Earth and Planetary Astrophysics - Abstract
We present new observations of the transmission spectrum of the hot Jupiter WASP-6b both from the ground with the Very Large Telescope (VLT) FOcal Reducer and Spectrograph (FORS2) from 0.45-0.83 $\mu$m, and space with the Transiting Exoplanet Survey Satellite (TESS) from 0.6-1.0 $\mu$m and the Hubble Space Telescope (HST) Wide Field Camera 3 from 1.12-1.65 $\mu$m. Archival data from the HST Space Telescope Imaging Spectrograph (STIS) and Spitzer is also reanalysed on a common Gaussian process framework, of which the STIS data show a good overall agreement with the overlapping FORS2 data. We also explore the effects of stellar heterogeneity on our observations and its resulting implications towards determining the atmospheric characteristics of WASP-6b. Independent of our assumptions for the level of stellar heterogeneity we detect Na I, K I and H$_2$O absorption features and constrain the elemental oxygen abundance to a value of [O/H] $\simeq -0.9\pm0.3$ relative to solar. In contrast, we find that the stellar heterogeneity correction can have significant effects on the retrieved distributions of the [Na/H] and [K/H] abundances, primarily through its degeneracy with the sloping optical opacity of scattering haze species within the atmosphere. Our results also show that despite this presence of haze, WASP-6b remains a favourable object for future atmospheric characterisation with upcoming missions such as the James Webb Space Telescope., Comment: Accepted to MNRAS
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- 2020
24. Unveiling cloudy exoplanets: the influence of cloud model choices on retrieval solutions
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Joanna K. Barstow
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Physics ,Earth and Planetary Astrophysics (astro-ph.EP) ,Haze ,010504 meteorology & atmospheric sciences ,Astronomy ,FOS: Physical sciences ,Astronomy and Astrophysics ,01 natural sciences ,Exoplanet ,Aerosol ,Space and Planetary Science ,Planet ,0103 physical sciences ,Hot Jupiter ,Radiative transfer ,Transit (astronomy) ,Astrophysics::Earth and Planetary Astrophysics ,Absorption (electromagnetic radiation) ,010303 astronomy & astrophysics ,Physics::Atmospheric and Oceanic Physics ,0105 earth and related environmental sciences ,Astrophysics - Earth and Planetary Astrophysics - Abstract
In recent years, it has become clear that a substantial fraction of transiting exoplanets have some form of aerosol present in their atmospheres. Transit spectroscopy - mostly of hot Jupiters, but also of some smaller planets - has provided evidence for this, in the form of steep downward slopes from blue to red in the optical part of the spectrum, and muted gas absorption features throughout. Retrieval studies seeking to constrain the composition of exoplanet atmospheres must therefore account for the presence of aerosols. However, clouds and hazes are complex physical phenomena, and the transit spectra that are currently available allow us to constrain only some of their properties. Therefore, representation of aerosols in retrieval models requires that they are described by only a few parameters, and this has been done in a variety of ways within the literature. Here, I investigate a range of parameterisations for exoplanet aerosol and their effects on retrievals from transmission spectra of hot Jupiters HD 189733b and HD 209458b. I find that results qualitatively agree for the cloud/haze itself regardless of the parameterisation used, and indeed using multiple approaches provides a more holistic picture; the retrieved abundance of H2O is also very robust to assumptions about aerosols. I also find strong evidence that aerosol on HD 209458b covers less than half of the terminator region, whilst the picture is less clear for HD 189733b., 15 pages, 10 figures. Accepted in MNRAS
- Published
- 2020
25. A comparison of exoplanet spectroscopic retrieval tools
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Quentin Changeat, Michael R. Line, Ryan Garland, Joanna K. Barstow, Ingo Waldmann, and Marco Rocchetto
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Physics ,Earth and Planetary Astrophysics (astro-ph.EP) ,010504 meteorology & atmospheric sciences ,James Webb Space Telescope ,Sigma ,FOS: Physical sciences ,Astronomy and Astrophysics ,Residual ,01 natural sciences ,Exoplanet ,Transmission (telecommunications) ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Planet ,0103 physical sciences ,Radiative transfer ,Noise (video) ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,0105 earth and related environmental sciences ,Remote sensing ,Astrophysics - Earth and Planetary Astrophysics - Abstract
Over the last several years, spectroscopic observations of transiting exoplanets have begun to uncover information about their atmospheres, including atmospheric composition and indications of the presence of clouds and hazes. Spectral retrieval is the leading technique for interpretation of transmission spectra and is employed by several teams using a variety of forward models and parameter estimation algorithms. However, different model suites have mostly been used in isolation and so it is unknown whether the results from each are comparable. As we approach the launch of the James Webb Space Telescope we anticipate advances in wavelength coverage, precision, and resolution of transit spectroscopic data, so it is important that the tools that will be used to interpret these information rich spectra are validated. To this end, we present an inter-model comparison of three retrieval suites: TauREx, NEMESIS and CHIMERA. We demonstrate that the forward model spectra are in good agreement (residual deviations on the order of 20 - 40 ppm), and discuss the results of cross retrievals between the three tools. Generally, the constraints from the cross retrievals are consistent with each other and with input values to within 1 sigma However, for high precision scenarios with error envelopes of order 30 ppm, subtle differences in the simulated spectra result in discrepancies between the different retrieval suites, and inaccuracies in retrieved values of several sigma. This can be considered analogous to substantial systematic/astrophysical noise in a real observation, or errors/omissions in a forward model such as molecular linelist incompleteness or missing absorbers., 25 pages, 21 figures. Accepted in MNRAS
- Published
- 2020
26. Into the UV: The Atmosphere of the Hot Jupiter HAT-P-41b Revealed
- Author
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Mark S. Marley, Nor Pirzkal, Thomas Mikal-Evans, Tiffany Kataria, Jeff A. Valenti, Kevin B. Stevenson, Ishan Mishra, David K. Sing, Hannah R. Wakeford, Jayesh M. Goyal, Peter Xiang Gao, Katy L. Chubb, Nikole K. Lewis, Nikolay Nikolov, Jessica Spake, Natasha E. Batalha, Joanna K. Barstow, Ryan J. MacDonald, Julianne I. Moses, Tom J. Wilson, Diana Powell, and Xi Zhang
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Physics ,Earth and Planetary Astrophysics (astro-ph.EP) ,010504 meteorology & atmospheric sciences ,Opacity ,Infrared ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Orders of magnitude (numbers) ,medicine.disease_cause ,01 natural sciences ,Exoplanet ,Atmosphere ,Grism ,Space and Planetary Science ,0103 physical sciences ,Hot Jupiter ,medicine ,Astrophysics::Earth and Planetary Astrophysics ,010303 astronomy & astrophysics ,Ultraviolet ,Astrophysics::Galaxy Astrophysics ,Astrophysics - Earth and Planetary Astrophysics ,0105 earth and related environmental sciences - Abstract
For solar-system objects, ultraviolet spectroscopy has been critical in identifying sources for stratospheric heating and measuring the abundances of a variety of hydrocarbon and sulfur-bearing species, produced via photochemical mechanisms, as well as oxygen and ozone. To date, less than 20 exoplanets have been probed in this critical wavelength range (0.2-0.4 um). Here we use data from Hubble's newly implemented WFC3 UVIS G280 grism to probe the atmosphere of the hot Jupiter HAT-P-41b in the ultraviolet through optical in combination with observations at infrared wavelengths. We analyze and interpret HAT-P-41b's 0.2-5.0 um transmission spectrum using a broad range of methodologies including multiple treatments of data systematics as well as comparisons with atmospheric forward, cloud microphysical, and multiple atmospheric retrieval models. Although some analysis and interpretation methods favor the presence of clouds or potentially a combination of Na, VO, AlO, and CrH to explain the ultraviolet through optical portions of HAT-P-41b's transmission spectrum, we find that the presence of a significant H- opacity provides the most robust explanation. We obtain a constraint for the abundance of H-, log(H-) = -8.65 +/- 0.62 in HAT-P-41b's atmosphere, which is several orders of magnitude larger than predictions from equilibrium chemistry for a 1700 - 1950 K hot Jupiter. We show that a combination of photochemical and collisional processes on hot hydrogen-dominated exoplanets can readily supply the necessary amount of H- and suggest that such processes are at work in HAT-P-41b and many other hot Jupiter atmospheres., Comment: 17 pages, 7 figures. Published in ApJL (October 8th 2020)
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- 2020
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27. The Hubble Space Telescope PanCET Program: An Optical to Infrared Transmission Spectrum of HAT-P-32Ab
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Vincent Bourrier, David K. Sing, Mercedes Lopez-Morales, Hannah R. Wakeford, Jorge Sanz-Forcada, Gregory W. Henry, Antonio García Muñoz, Claire Baxter, Ofer Cohen, Panayotis Lavvas, Lars A. Buchhave, Joanna K. Barstow, Nikolay Nikolov, Munazza Alam, Thomas Mikal-Evans, Michael H. Williamson, Jean-Michel Desert, Harvard-Smithsonian Center for Astrophysics (CfA), Smithsonian Institution-Harvard University [Cambridge], Space Telescope Science Institute (STSci), Department of Physics [Baltimore], University of Maryland [Baltimore County] (UMBC), University of Maryland System-University of Maryland System, Center of Excellence in Information Systems, Anton Pannekoek Institute for Astronomy, University of Amsterdam [Amsterdam] (UvA), MIT Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology (MIT), Observatoire Astronomique de l'Université de Genève (ObsGE), Université de Genève (UNIGE), Groupe de spectrométrie moléculaire et atmosphérique (GSMA), Université de Reims Champagne-Ardenne (URCA)-Centre National de la Recherche Scientifique (CNRS), Technische Universität Berlin (TU), Alam, M. K. [0000-0003-4157-832X], López Morales, M. [0000-0003-3204-8183], Nikolov, N. [0000-0002-6500-3574], Sing, D. K. [0000-0001-6050-7645], Henry, G. W. [0000-0003-4155-8513], Baxter, C. [0000-0003-3438-843X], Désert, J. M. [0000-0002-0875-8401], Barstow, J. K. [0000-0003-3726-5419], Mikal Evans, T. [0000-0001-5442-1300], Bourrier, V. [0000-0002-9148-034X], Lavvas, P. [0000-0002-5360-3660], Wakeford, H. R. [0000-0003-4328-3867], Forcada, J. S. [0000-0002-1600-7835], Buchhave, L. A. [0000-0003-1605-5666], Cohen, O. [0000-0003-3721-0215], García Muñoz, A. [0000-0003-1756-4825], National Aeronautics & Space Administration (NASA), NAS 5-26555, HST GO programs, 14767 14260, Space Telescope Science Institute, HST-GO-14767, Agencia Estatal de Investigación (AEI), National Aeronautics and Space Administration (NASA), European Research Council (ERC), and Low Energy Astrophysics (API, FNWI)
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010504 meteorology & atmospheric sciences ,Infrared ,[SDU.ASTR.CO]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO] ,Hot Jupiters ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Planet ,0103 physical sciences ,Hot Jupiter ,Astrophysics::Solar and Stellar Astrophysics ,010303 astronomy & astrophysics ,Space Telescope Imaging Spectrograph ,ComputingMilieux_MISCELLANEOUS ,Astrophysics::Galaxy Astrophysics ,0105 earth and related environmental sciences ,Eclipse ,Physics ,planets and satellites: atmospheres ,[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph] ,planets and satellites: individual (HAT-P-32Ab) ,Exoplanets ,planets and satellites: composition ,Astronomy and Astrophysics ,Exoplanet ,Photometry (astronomy) ,Exoplanet atmospheric composition ,13. Climate action ,Space and Planetary Science ,[SDU]Sciences of the Universe [physics] ,Astrophysics::Earth and Planetary Astrophysics ,Wide Field Camera 3 ,Exoplanet atmospheres - Abstract
We present a 0.3-5 μm transmission spectrum of the hot Jupiter HAT-P-32Ab observed with the Space Telescope Imaging Spectrograph and Wide Field Camera 3 instruments mounted on the Hubble Space Telescope, combined with Spitzer Infrared Array Camera photometry. The spectrum is composed of 51 spectrophotometric bins with widths ranging between 150 and 400 Å, measured to a median precision of 215 ppm. Comparisons of the observed transmission spectrum to a grid of 1D radiative-convective equilibrium models indicate the presence of clouds/hazes, consistent with previous transit observations and secondary eclipse measurements. To provide more robust constraints on the planet's atmospheric properties, we perform the first full optical to infrared retrieval analysis for this planet. The retrieved spectrum is consistent with a limb temperature of 1248+9292 K, a thick cloud deck, enhanced Rayleigh scattering, and ∼10× solar H2O abundance. We find log(Z/Z o˙) =2.41+0.06-0.07, and compare this measurement with the mass-metallicity relation derived for the solar system., With funding from the Spanish government through the "María de Maeztu Unit of Excellence" accreditation (MDM-2017-0737)
- Published
- 2020
28. A Hubble PanCET Study of HAT-P-11b: A Cloudy Neptune with a Low Atmospheric Metallicity
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Nikolay Nikolov, Megan Mansfield, Hannah R. Wakeford, Michael Zhang, Thomas Mikal-Evans, Ian Wong, David K. Sing, Gregory W. Henry, Yayaati Chachan, Nikole K. Lewis, Tiffany Kataria, Mercedes Lopez-Morales, Peter Gao, Björn Benneke, Jacob L. Bean, Joanna K. Barstow, and Heather Knutson
- Subjects
Earth and Planetary Astrophysics (astro-ph.EP) ,Physics ,Solar System ,010504 meteorology & atmospheric sciences ,Metallicity ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Wavelength ,Transmission (telecommunications) ,Space and Planetary Science ,Neptune ,Planet ,0103 physical sciences ,Transit (astronomy) ,Astrophysics::Earth and Planetary Astrophysics ,Absorption (electromagnetic radiation) ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,0105 earth and related environmental sciences ,Astrophysics - Earth and Planetary Astrophysics - Abstract
We present the first comprehensive look at the $0.35-5$ $\mu$m transmission spectrum of the warm ($\sim 800$ K) Neptune HAT-P-11b derived from thirteen individual transits observed using the Hubble and Spitzer Space Telescopes. Along with the previously published molecular absorption feature in the $1.1-1.7$ $\mu$m bandpass, we detect a distinct absorption feature at 1.15 $\mu$m and a weak feature at 0.95 $\mu$m, indicating the presence of water and/or methane with a combined significance of 4.4 $\sigma$. We find that this planet's nearly flat optical transmission spectrum and attenuated near-infrared molecular absorption features are best-matched by models incorporating a high-altitude cloud layer. Atmospheric retrievals using the combined $0.35-1.7$ $\mu$m HST transmission spectrum yield strong constraints on atmospheric cloud-top pressure and metallicity, but we are unable to match the relatively shallow Spitzer transit depths without under-predicting the strength of the near-infrared molecular absorption bands. HAT-P-11b's HST transmission spectrum is well-matched by predictions from our microphysical cloud models. Both forward models and retrievals indicate that HAT-P-11b most likely has a relatively low atmospheric metallicity ($, Comment: Accepted for publication in AJ. 33 pages, 23 figures
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- 2019
29. Telling twins apart: exo-Earths and Venuses with transit spectroscopy
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Sarah Kendrew, Joanna K. Barstow, Patrick G. J. Irwin, Suzanne Aigrain, and Leigh N. Fletcher
- Subjects
010504 meteorology & atmospheric sciences ,FOS: Physical sciences ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,01 natural sciences ,Astrobiology ,law.invention ,Atmosphere ,Telescope ,Planet ,law ,0103 physical sciences ,Transit (astronomy) ,010303 astronomy & astrophysics ,Physics::Atmospheric and Oceanic Physics ,0105 earth and related environmental sciences ,Earth and Planetary Astrophysics (astro-ph.EP) ,Physics ,James Webb Space Telescope ,Astrophysics::Instrumentation and Methods for Astrophysics ,Astronomy and Astrophysics ,Exoplanet ,Space and Planetary Science ,Terrestrial planet ,Astrophysics::Earth and Planetary Astrophysics ,Circumstellar habitable zone ,Astrophysics - Earth and Planetary Astrophysics - Abstract
The planned launch of the James Webb Space Telescope in 2018 will herald a new era of exoplanet spectroscopy. JWST will be the first telescope sensitive enough to potentially characterize terrestrial planets from their transmission spectra. In this work, we explore the possibility that terrestrial planets with Venus-type and Earth-type atmospheres could be distinguished from each other using spectra obtained by JWST. If we find a terrestrial planet close to the liquid water habitable zone of an M5 star within a distance of 10 parsecs, it would be possible to detect atmospheric ozone if present in large enough quantities, which would enable an oxygen-rich atmosphere to be identified. However, the cloudiness of a Venus-type atmosphere would inhibit our ability to draw firm conclusions about the atmospheric composition, making any result ambiguous. Observing small, temperate planets with JWST requires significant investment of resources, with single targets requiring of order 100 transits to achieve sufficient signal to noise. The possibility of detecting a crucial feature such as the ozone signature would need to be carefully weighed against the likelihood of clouds obscuring gas absorption in the spectrum., Comment: 12 pages, 9 figures. This is a pre-copyedited, author-produced PDF of an article accepted for publication in MNRAS following peer review
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- 2016
30. An absolute sodium abundance for a cloud-free 'hot Saturn' exoplanet
- Author
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Aarynn L. Carter, Adam J. Burgasser, Nikolay Nikolov, David K. Sing, Zafar Rustamkulov, Jack McCleery, Coel Hellier, Neale P. Gibson, Benjamin Drummond, Josef Baines, Nathan J. Mayne, Nikku Madhusudhan, Christiane Helling, Ernst J. W. de Mooij, Jonathan J. Fortney, Gilda E. Ballester, Barry Smalley, Tiffany Kataria, Joanna K. Barstow, Thomas M. Evans, Hannah R. Wakeford, Jayesh M. Goyal, Jessica Spake, University of St Andrews. School of Physics and Astronomy, University of St Andrews. St Andrews Centre for Exoplanet Science, Nikku, Madhusudhan [0000-0002-4869-000X], and Apollo - University of Cambridge Repository
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010504 meteorology & atmospheric sciences ,Opacity ,Metallicity ,NDAS ,FOS: Physical sciences ,Astrophysics ,7. Clean energy ,01 natural sciences ,Spectral line ,Planet ,Saturn ,0103 physical sciences ,QB460 ,QB Astronomy ,Astrophysics::Solar and Stellar Astrophysics ,Absorption (electromagnetic radiation) ,010303 astronomy & astrophysics ,R2C ,QC ,Astrophysics::Galaxy Astrophysics ,QB600 ,0105 earth and related environmental sciences ,QB ,Physics ,Earth and Planetary Astrophysics (astro-ph.EP) ,Very Large Telescope ,Multidisciplinary ,~DC~ ,Exoplanet ,QC Physics ,13. Climate action ,astro-ph.EP ,Astrophysics::Earth and Planetary Astrophysics ,BDC ,Astrophysics - Earth and Planetary Astrophysics - Abstract
Broad absorption signatures from alkali metals, such as the sodium (Na I) and potassium (K I) resonance doublets, have long been predicted in the optical atmospheric spectra of cloud-free irradiated gas-giant exoplanets1,2,3. However, observations have only revealed the narrow cores of these features rather than the full pressure-broadened profiles4-6. Cloud and haze opacity at the day-night planetary terminator are considered responsible for obscuring the absorption-line wings, which hinders constraints on absolute atmospheric abundances7-9. Here we present an optical transmission spectrum for the 'hot-Saturn' WASP-96b obtained with the Very Large Telescope, which exhibits the complete pressure-broadened profile of the sodium absorption feature. The spectrum is in excellent agreement with cloud-free, solar-abundance models assuming chemical equilibrium. We are able to measure a precise, absolute sodium abundance of log\epsilon_Na=6.9+0.6-0.4, and use it as a proxy to the planet's atmospheric metallicity relative to the solar value (Z_p/Z_\star=2.3+8.9/--1.7). This result is consistent with the mass-metallicity trend observed for solar-system planets and exoplanets10-12., Comment: Published in Nature
- Published
- 2018
31. A Framework for Prioritizing the TESS Planetary Candidates Most Amenable to Atmospheric Characterization
- Author
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Daniel D. B. Koll, Nicolas B. Cowan, Emily Rauscher, Jessie L. Christiansen, Dana R. Louie, Miguel de Val-Borro, David K. Sing, Keivan G. Stassun, Zach Berta-Thompson, Stephen R. Kane, Thomas G. Beatty, Diana Dragomir, Joanna K. Barstow, Natasha E. Batalha, Eliza M.-R. Kempton, Robert T. Zellem, Jeff A. Valenti, Drake Deming, Matthias Mallonn, Eric Gaidos, Kevin Heng, Valerio Nascimbeni, Laura Kreidberg, Evgenya L. Shkolnik, Sara Seager, Ian J. M. Crossfield, Jayne Birkby, Caroline V. Morley, David Charbonneau, Megan Mansfield, Carolina von Essen, Sarah Ballard, Lars A. Buchhave, Enric Palle, Elisa V. Quintana, Mercedes Lopez-Morales, Alessandro Sozzetti, René Doyon, Norio Narita, Jacob L. Bean, Thomas Barclay, Renyu Hu, Mark R. Swain, Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences, MIT Kavli Institute for Astrophysics and Space Research, and Low Energy Astrophysics (API, FNWI)
- Subjects
JWST ,010504 meteorology & atmospheric sciences ,530 Physics ,detection [planets and satellites] ,Computer science ,FOS: Physical sciences ,MIDINFRARED INSTRUMENT ,01 natural sciences ,Astrobiology ,Planet ,0103 physical sciences ,010303 astronomy & astrophysics ,0105 earth and related environmental sciences ,Earth and Planetary Astrophysics (astro-ph.EP) ,STAR ,520 Astronomy ,Astrophysics::Instrumentation and Methods for Astrophysics ,WEBB-SPACE-TELESCOPE ,Astronomy and Astrophysics ,Thermal emission ,atmospheres [planets and satellites] ,EXOPLANETS ,Mass measurement ,Exoplanet ,Characterization (materials science) ,Rapid identification ,Radial velocity ,Stars ,Space and Planetary Science ,TEMPERATE TERRESTRIAL PLANETS ,Astrophysics::Earth and Planetary Astrophysics ,ROCKY ,Astrophysics - Earth and Planetary Astrophysics - Abstract
A key legacy of the recently launched TESS mission will be to provide the astronomical community with many of the best transiting exoplanet targets for atmospheric characterization. However, time is of the essence to take full advantage of this opportunity. JWST, although delayed, will still complete its nominal five year mission on a timeline that motivates rapid identification, confirmation, and mass measurement of the top atmospheric characterization targets from TESS. Beyond JWST, future dedicated missions for atmospheric studies such as ARIEL require the discovery and confirmation of several hundred additional sub-Jovian size planets (R_p < 10 R_Earth) orbiting bright stars, beyond those known today, to ensure a successful statistical census of exoplanet atmospheres. Ground-based ELTs will also contribute to surveying the atmospheres of the transiting planets discovered by TESS. Here we present a set of two straightforward analytic metrics, quantifying the expected signal-to-noise in transmission and thermal emission spectroscopy for a given planet, that will allow the top atmospheric characterization targets to be readily identified among the TESS planet candidates. Targets that meet our proposed threshold values for these metrics would be encouraged for rapid follow-up and confirmation via radial velocity mass measurements. Based on the catalog of simulated TESS detections by Sullivan et al. (2015), we determine appropriate cutoff values of the metrics, such that the TESS mission will ultimately yield a sample of $\sim300$ high-quality atmospheric characterization targets across a range of planet size bins, extending down to Earth-size, potentially habitable worlds., accepted to PASP
- Published
- 2018
32. An Optical Transmission Spectrum for the Ultra-hot Jupiter WASP-121b Measured with the Hubble Space Telescope
- Author
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David K. Sing, David Ehrenreich, Sarah D. Blumenthal, Kevin Zahnle, Lotfi Ben-Jaffel, Panayotis Lavvas, Mercedes Lopez-Morales, Mark S. Marley, Tiffany Kataria, Gilda E. Ballester, Joanna K. Barstow, Lars A. Buchhave, Hannah R. Wakeford, Vincent Bourrier, Alain Lecavelier des Etangs, Thomas M. Evans, Munazza K. Alam, Jayesh M. Goyal, Pascal Tremblin, Jorge Sanz-Forcada, Eric Hébrard, Nikole K. Lewis, Antonio García Muñoz, Gregory W. Henry, Michael H. Williamson, Benjamin Drummond, Nikolay Nikolov, MIT Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology (MIT), Johns Hopkins University (JHU), University of Exeter, NASA Ames Research Center Cooperative for Research in Earth Science in Technology (ARC-CREST), NASA Ames Research Center (ARC), University College of London [London] (UCL), Harvard-Smithsonian Center for Astrophysics (CfA), Smithsonian Institution-Harvard University [Cambridge], Centro de Astrobiologia [Madrid] (CAB), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Carl Sagan Institute, Cornell University [New York], Groupe de spectrométrie moléculaire et atmosphérique (GSMA), Université de Reims Champagne-Ardenne (URCA)-Centre National de la Recherche Scientifique (CNRS), Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, Institut d'Astrophysique de Paris (IAP), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Observatoire Astronomique de l'Université de Genève (ObsGE), Université de Genève (UNIGE), School of Physics and Astronomy [Exeter], Zentrum für Astronomie und Astrophysik [Berlin] (ZAA), Technische Universität Berlin (TU), Maison de la Simulation (MDLS), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Recherche en Informatique et en Automatique (Inria)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Space Telescope Science Institute (STSci), National Space Institute [Lyngby] (DTU Space), Technical University of Denmark [Lyngby] (DTU), Stiftelsen for INdustriell og TEknisk Forskning Digital [Trondheim] (SINTEF Digital), Tennessee State University, Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), University of Geneva [Switzerland], Harvard University [Cambridge]-Smithsonian Institution, Département d'Astrophysique (ex SAP) (DAP), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, NASA Goddard Space Flight Center (GSFC), Niels Bohr Institute [Copenhagen] (NBI), Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU), Harvard University-Smithsonian Institution, Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université de Genève = University of Geneva (UNIGE), Technical University of Berlin / Technische Universität Berlin (TU), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut National de Recherche en Informatique et en Automatique (Inria)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Danmarks Tekniske Universitet = Technical University of Denmark (DTU)
- Subjects
Opacity ,[SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP] ,FOS: Physical sciences ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,7. Clean energy ,01 natural sciences ,atmospheresplanets and satellites ,methods ,Atmosphere ,symbols.namesake ,gaseous planets ,0103 physical sciences ,Hot Jupiter ,Thermal ,Astrophysics::Solar and Stellar Astrophysics ,observational [Methods] ,Rayleigh scattering ,010303 astronomy & astrophysics ,ComputingMilieux_MISCELLANEOUS ,Space Telescope Imaging Spectrograph ,Astrophysics::Galaxy Astrophysics ,Physics ,Earth and Planetary Astrophysics (astro-ph.EP) ,[SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR] ,010308 nuclear & particles physics ,Astronomy and Astrophysics ,Spectral bands ,Wavelength ,gaseous planets [Planets and satellites] ,13. Climate action ,Space and Planetary Science ,observationalplanets and satellites ,symbols ,atmospheres [Planets and satellites] ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics - Earth and Planetary Astrophysics - Abstract
We present an atmospheric transmission spectrum for the ultra-hot Jupiter WASP-121b, measured using the Space Telescope Imaging Spectrograph (STIS) onboard the Hubble Space Telescope (HST). Across the 0.47-1 micron wavelength range, the data imply an atmospheric opacity comparable to - and in some spectroscopic channels exceeding - that previously measured at near-infrared wavelengths (1.15-1.65 micron). Wavelength-dependent variations in the opacity rule out a gray cloud deck at a confidence level of 3.8-sigma and may instead be explained by VO spectral bands. We find a cloud-free model assuming chemical equilibrium for a temperature of 1500K and metal enrichment of 10-30x solar matches these data well. Using a free-chemistry retrieval analysis, we estimate a VO abundance of -6.6(-0.3,+0.2) dex. We find no evidence for TiO and place a 3-sigma upper limit of -7.9 dex on its abundance, suggesting TiO may have condensed from the gas phase at the day-night limb. The opacity rises steeply at the shortest wavelengths, increasing by approximately five pressure scale heights from 0.47 to 0.3 micron in wavelength. If this feature is caused by Rayleigh scattering due to uniformly-distributed aerosols, it would imply an unphysically high temperature of 6810+/-1530K. One alternative explanation for the short-wavelength rise is absorption due to SH (mercapto radical), which has been predicted as an important product of non-equilibrium chemistry in hot Jupiter atmospheres. Irrespective of the identity of the NUV absorber, it likely captures a significant amount of incident stellar radiation at low pressures, thus playing a significant role in the overall energy budget, thermal structure, and circulation of the atmosphere., Comment: Accepted for publication in The Astronomical Journal
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- 2018
33. The Long wave (11–16 μm) spectrograph for the EChO M3 Mission Candidate study
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D. Freeman, Pgj Irwin, Marc Ferlet, Jon Temple, M. Tecza, S. B. Calcutt, Joanna K. Barstow, Leigh N. Fletcher, Neil Bowles, and Jane Hurley
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Physics ,Zodiacal light ,Spectrometer ,business.industry ,Astrophysics::Instrumentation and Methods for Astrophysics ,Astronomy ,Astronomy and Astrophysics ,Exoplanet ,law.invention ,Telescope ,Optics ,Space and Planetary Science ,law ,Beam expander ,Astrophysics::Earth and Planetary Astrophysics ,Prism ,Infrared detector ,business ,Spectrograph - Abstract
The results for the design study of the Long Wave Infrared Module (LWIR), a goal spectroscopic channel for the EChO ESA medium class candidate mission, are presented. The requirements for the LWIR module were to provide coverage of the 11–16 μm spectral range at a moderate resolving power of at least R = 30, whilst minimising noise contributions above photon due to the thermal background of the EChO instrument and telescope, and astrophysical sources such as the zodiacal light. The study output module design is a KRS-6 prism spectrograph with aluminium mirror beam expander and coated germanium lenses for the final focusing elements. Thermal background considerations led to enclosing the beam in a baffle cooled to approximately 25–29 K. To minimise diffuse astrophysical background contributions due to the zodiacal light, anamorphic designs were considered in addition to the elliptical input beam provided by the EChO telescope. Given the requirement that measurements in this waveband place on the performance of the infrared detector array, an additional study on the likely scientific return with lower resolving power (R
- Published
- 2015
34. Transit spectroscopy with James Webb Space Telescope: systematics, starspots and stitching
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Joanna K. Barstow, Suzanne Aigrain, Leigh N. Fletcher, Sarah Kendrew, and Patrick G. J. Irwin
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Physics ,James Webb Space Telescope ,Starspot ,Astrophysics::Instrumentation and Methods for Astrophysics ,Astronomy ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Exoplanet ,Spectral line ,Stars ,Space and Planetary Science ,Planet ,Hot Jupiter ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,Transit (astronomy) - Abstract
The James Webb Space Telescope (JWST) is predicted to make great advances in the field of exoplanet atmospheres. Its 25 m2 mirror means that it can reach unprecedented levels of precision in observations of transit spectra, and can thus characterise the atmospheres of planets orbiting stars several hundred pc away. Its coverage of the infrared spectral region between 0.6 and 28 {\mu}m allows the abundances of key molecules to be probed during the transit of a planet in front of the host star, and when the same planet is eclipsed constraints can be placed on its temperature structure. In this work, we explore the possibility of using low-spectral-resolution observations by JWST/NIRSpec and JWST/MIRI-LRS together to optimise wavelength coverage and break degeneracies in the atmospheric retrieval problem for a range of exoplanets from hot Jupiters to super Earths. This approach involves stitching together non-simultaneous observations in different wavelength regions, rendering it necessary to consider the effect of time-varying instrumental and astrophysical systematics. We present the results of a series of retrieval feasibility tests examining the effects of instrument systematics and star spots on the recoverability of the true atmospheric state, and demonstrate that correcting for these systematics is key for successful exoplanet science with JWST.
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- 2015
35. The transit spectra of Earth and Jupiter
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Joanna K. Barstow, Neil Bowles, Patrick G. J. Irwin, Suzanne Aigrain, Jae-Min Lee, and Leigh N. Fletcher
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Earth and Planetary Astrophysics (astro-ph.EP) ,Physics ,Secondary atmosphere ,FOS: Physical sciences ,Astronomy ,Astronomy and Astrophysics ,Exoplanet ,Jupiter ,Space and Planetary Science ,Planet ,Hot Jupiter ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,Transit (astronomy) ,Planetary mass ,Jupiter mass ,Astrophysics - Earth and Planetary Astrophysics - Abstract
In recent years, an increasing number of observations have been made of the transits of ‘Hot Jupiters’, such as HD 189733b, about their parent stars from the visible through to mid-infrared wavelengths, which have been modelled to derive the likely atmospheric structure and composition of these planets. As measurement techniques improve, the measured transit spectra of ‘Super-Earths’ such as GJ 1214b are becoming better constrained, allowing model atmospheric states to be fitted for this class of planet also. While it is not yet possible to constrain the atmospheric states of small planets such as the Earth or cold planets like Jupiter, it is hoped that this might become practical in the coming decades and if so, it is of interest to determine what we might infer from such measurements. In this work we have constructed atmospheric models of the Solar System planets from 0.4 to 15.5 μm that are consistent with ground-based and satellite observations and from these calculate the primary transit and secondary eclipse spectra (with respect to the Sun and typical M-dwarfs) that would be observed by a ‘remote observer’, many light years away. From these spectra we test what current retrieval models might infer about their atmospheric states and compare these with the ‘ground truths’ in order to assess: (a) the inherent uncertainties in transit spectra observations; (b) the relative merits of primary transit and secondary eclipse spectra; and (c) the advantages of acquiring directly imaged spectra of these planets. We find that observing secondary eclipses of the Solar System would not give sufficient information for determining atmospheric properties with 10 m-diameter telescopes from a distance of 10 light years, but that primary transits give much better information. We find that a single transit of Jupiter in front of the Sun could potentially be used to determine temperature and stratospheric composition, but for the Earth the mean atmospheric composition could only be determined if it were orbiting a much smaller M-dwarf. For both Jupiter and Earth we note that direct imaging with sufficient nulling of the light from the parent star theoretically provides the best method of determining the atmospheric properties of such planets.
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- 2014
36. The Very Low Albedo of WASP-12b from Spectral Eclipse Observations with Hubble
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Heather Knutson, Neale P. Gibson, Joel C. Schwartz, Joshua D. Lothringer, David K. Sing, Joanna K. Barstow, Thomas M. Evans, Nikolay Nikolov, Taylor J. Bell, Björn Benneke, Travis Barman, Nicolas B. Cowan, Ian J. M. Crossfield, and Tiffany Kataria
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010504 meteorology & atmospheric sciences ,FOS: Physical sciences ,Astrophysics ,01 natural sciences ,photometric [techniques] ,symbols.namesake ,Geometric albedo ,Planet ,0103 physical sciences ,Hot Jupiter ,Astrophysics::Solar and Stellar Astrophysics ,Rayleigh scattering ,individual: WASP-12 [stars] ,010303 astronomy & astrophysics ,Space Telescope Imaging Spectrograph ,0105 earth and related environmental sciences ,Eclipse ,Physics ,Earth and Planetary Astrophysics (astro-ph.EP) ,Astronomy and Astrophysics ,Albedo ,atmospheres [planets and satellites] ,Exoplanet ,13. Climate action ,Space and Planetary Science ,symbols ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics - Earth and Planetary Astrophysics - Abstract
We present an optical eclipse observation of the hot Jupiter WASP-12b using the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. These spectra allow us to place an upper limit of $A_g < 0.064$ (97.5% confidence level) on the planet's white light geometric albedo across 290--570 nm. Using six wavelength bins across the same wavelength range also produces stringent limits on the geometric albedo for all bins. However, our uncertainties in eclipse depth are $\sim$40% greater than the Poisson limit and may be limited by the intrinsic variability of the Sun-like host star --- the solar luminosity is known to vary at the $10^{-4}$ level on a timescale of minutes. We use our eclipse depth limits to test two previously suggested atmospheric models for this planet: Mie scattering from an aluminum-oxide haze or cloud-free Rayleigh scattering. Our stringent nondetection rules out both models and is consistent with thermal emission plus weak Rayleigh scattering from atomic hydrogen and helium. Our results are in stark contrast with those for the much cooler HD 189733b, the only other hot Jupiter with spectrally resolved reflected light observations; those data showed an increase in albedo with decreasing wavelength. The fact that the first two exoplanets with optical albedo spectra exhibit significant differences demonstrates the importance of spectrally resolved reflected light observations and highlights the great diversity among hot Jupiters., 8 pages, 4 figures, 1 table, published in ApJL, in press
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- 2017
37. An ultrahot gas-giant exoplanet with a stratosphere
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Hannah R. Wakeford, Roxana Lupu, David K. Sing, Gregory W. Henry, Mark S. Marley, Joanna K. Barstow, Mercedes Lopez-Morales, Alain Lecavelier des Etangs, David S. Amundsen, Ofer Cohen, Tiffany Kataria, Pascal Tremblin, Jorge Sanz-Forcada, Panayotis Lavvas, Avi Mandell, Lars A. Buchhave, Antonio García Muñoz, Gilda E. Ballester, Nikolay Nikolov, Heather Knutson, Lotfi Ben-Jaffel, Drake Deming, Nikole K. Lewis, Jayesh M. Goyal, Thomas M. Evans, David Ehrenreich, Vincent Bourrier, University of Exeter, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), NASA Goddard Space Flight Center (GSFC), University of Maryland [College Park], University of Maryland System, NASA Ames Research Center Cooperative for Research in Earth Science in Technology (ARC-CREST), NASA Ames Research Center (ARC), Columbia University [New York], NASA Goddard Institute for Space Studies (GISS), Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, University College of London [London] (UCL), Institut d'Astrophysique de Paris (IAP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Observatoire Astronomique de l'Université de Genève (ObsGE), Université de Genève = University of Geneva (UNIGE), Niels Bohr Institute [Copenhagen] (NBI), Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH), University of Massachusetts [Lowell] (UMass Lowell), University of Massachusetts System (UMASS), Technical University of Berlin / Technische Universität Berlin (TU), Tennessee State University, Caltech Department of Astronomy [Pasadena], California Institute of Technology (CALTECH), Groupe de spectrométrie moléculaire et atmosphérique (GSMA), Université de Reims Champagne-Ardenne (URCA)-Centre National de la Recherche Scientifique (CNRS), Space Telescope Science Institute (STSci), Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University-Smithsonian Institution, Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Maison de la Simulation (MDLS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut National de Recherche en Informatique et en Automatique (Inria)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Bay Area Environmental Research Institute (BAER), ANR-12-BS05-0012,Exo-Atmos,Atmosphère et Evaporation des Exoplanètes(2012), European Project: 247060,EC:FP7:ERC,ERC-2009-AdG,PEPS(2010), European Project: 336792,EC:FP7:ERC,ERC-2013-StG,CREATES(2013), California Institute of Technology (CALTECH)-NASA, Université de Genève (UNIGE), University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU), Technische Universität Berlin (TU), Smithsonian Institution-Harvard University [Cambridge], Centre National de la Recherche Scientifique (CNRS)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Recherche en Informatique et en Automatique (Inria)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Harvard University [Cambridge]-Smithsonian Institution
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010504 meteorology & atmospheric sciences ,Infrared ,Gas giant ,[PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP] ,FOS: Physical sciences ,01 natural sciences ,Atmosphere ,0103 physical sciences ,[PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph] ,010303 astronomy & astrophysics ,Stratosphere ,Astrophysics::Galaxy Astrophysics ,Physics::Atmospheric and Oceanic Physics ,0105 earth and related environmental sciences ,Discoveries of exoplanets ,Physics ,Earth and Planetary Astrophysics (astro-ph.EP) ,Multidisciplinary ,Astronomy ,[PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR] ,Exoplanet ,13. Climate action ,Astrophysics::Earth and Planetary Astrophysics ,Kepler-62e ,Kepler-62c ,Astrophysics - Earth and Planetary Astrophysics - Abstract
Infrared radiation emitted from a planet contains information about the chemical composition and vertical temperature profile of its atmosphere. If upper layers are cooler than lower layers, molecular gases will produce absorption features in the planetary thermal spectrum. Conversely, if there is a stratosphere - where temperature increases with altitude - these molecular features will be observed in emission. It has been suggested that stratospheres could form in highly irradiated exoplanets, but the extent to which this occurs is unresolved both theoretically and observationally. A previous claim for the presence of a stratosphere remains open to question, owing to the challenges posed by the highly variable host star and the low spectral resolution of the measurements. Here we report a near-infrared thermal spectrum for the ultrahot gas giant WASP-121b, which has an equilibrium temperature of approximately 2,500 kelvin. Water is resolved in emission, providing a detection of an exoplanet stratosphere at 5-sigma confidence. These observations imply that a substantial fraction of incident stellar radiation is retained at high altitudes in the atmosphere, possibly by absorbing chemical species such as gaseous vanadium oxide and titanium oxide., This is the authors' version of the manuscript. 23 pages, 9 figures, 4 tables
- Published
- 2017
38. Hubble PanCET: an isothermal day-side atmosphere for the bloated gas-giant HAT-P-32Ab
- Author
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Hannah R. Wakeford, David Ehrenreich, A. Lecavelier des Etangs, Joanna K. Barstow, M. Lopez-Morales, A. García Muñoz, Gilda E. Ballester, Nikolay Nikolov, Thomas M. Evans, Gregory W. Henry, Avi Mandell, Jorge Sanz-Forcada, Heather Knutson, Panayotis Lavvas, Lars A. Buchhave, Vincent Bourrier, Michael H. Williamson, Jayesh M. Goyal, David K. Sing, Ofer Cohen, Tiffany Kataria, Lotfi Ben-Jaffel, Drake Deming, Nikole K. Lewis, Microsystems Ltd., Bulgarie, Department of Physics and Astronomy [Leicester], University of Leicester, AstroParticule et Cosmologie (APC (UMR_7164)), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Groupe de spectrométrie moléculaire et atmosphérique (GSMA), Université de Reims Champagne-Ardenne (URCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de l'intégration, du matériau au système (IMS), Université Sciences et Technologies - Bordeaux 1-Institut Polytechnique de Bordeaux-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), Laboratoire d'Astrophysique de Grenoble (LAOG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), University of Exeter, Tennessee State University, Harvard-Smithsonian Center for Astrophysics (CfA), Harvard University-Smithsonian Institution, Zentrum für Astronomie und Astrophysik [Berlin] (ZAA), Technical University of Berlin / Technische Universität Berlin (TU), Institut d'Astrophysique de Paris (IAP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, University College of London [London] (UCL), Observatoire Astronomique de l'Université de Genève (ObsGE), Université de Genève = University of Geneva (UNIGE), Niels Bohr Institute [Copenhagen] (NBI), Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH), Center for Atmospheric Research [Lowell] (UMLCAR), University of Massachusetts [Lowell] (UMass Lowell), University of Massachusetts System (UMASS)-University of Massachusetts System (UMASS), University of Maryland [College Park], University of Maryland System, California Institute of Technology (CALTECH), Space Telescope Science Institute (STSci), NASA Goddard Space Flight Center (GSFC), This work has been carried out in the frame of the National Centre for Competence in Research PlanetS supported by the Swiss National Science Foundation (SNSF). Leverhulme Trust Research Project Grant, and European Project: 724427,Future of upper atmospheric characterisation of exoplanets with spectroscopy
- Subjects
planets and satellites: individual: HAT-P-32Ab ,FOS: Physical sciences ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,0103 physical sciences ,Economic history ,media_common.cataloged_instance ,Astrophysics::Solar and Stellar Astrophysics ,European union ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,ComputingMilieux_MISCELLANEOUS ,media_common ,planets and satellites: atmospheres ,Earth and Planetary Astrophysics (astro-ph.EP) ,Physics ,[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph] ,010308 nuclear & particles physics ,European research ,Astronomy ,Astronomy and Astrophysics ,Space and Planetary Science ,stars: individual: HAT-P-32A ,Astrophysics::Earth and Planetary Astrophysics ,techniques: spectroscopic ,Astrophysics - Earth and Planetary Astrophysics - Abstract
We present a thermal emission spectrum of the bloated hot Jupiter HAT-P-32Ab from a single eclipse observation made in spatial scan mode with the Wide Field Camera 3 (WFC3) aboard the Hubble Space Telescope (HST). The spectrum covers the wavelength regime from 1.123 to 1.644 microns which is binned into 14 eclipse depths measured to an averaged precision of 104 parts-per million. The spectrum is unaffected by a dilution from the close M-dwarf companion HAT-P-32B, which was fully resolved. We complemented our spectrum with literature results and performed a comparative forward and retrieval analysis with the 1D radiative-convective ATMO model. Assuming solar abundance of the planet atmosphere, we find that the measured spectrum can best be explained by the spectrum of a blackbody isothermal atmosphere with Tp = 1995 +/- 17K, but can equally-well be described by a spectrum with modest thermal inversion. The retrieved spectrum suggests emission from VO at the WFC3 wavelengths and no evidence of the 1.4 micron water feature. The emission models with temperature profiles decreasing with height are rejected at a high confidence. An isothermal or inverted spectrum can imply a clear atmosphere with an absorber, a dusty cloud deck or a combination of both. We find that the planet can have continuum of values for the albedo and recirculation, ranging from high albedo and poor recirculation to low albedo and efficient recirculation. Optical spectroscopy of the planet's day-side or thermal emission phase curves can potentially resolve the current albedo with recirculation degeneracy., 14 pages, 10 figures, 3 tables, accepted for publication in MNRAS
- Published
- 2017
39. HST PanCET Program: A Cloudy Atmosphere for the Promising JWST Target WASP-101b
- Author
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Lotfi Ben-Jaffel, Avi Mandell, David K. Sing, Panayotis Lavvas, Hannah R. Wakeford, Lars A. Buchhave, Vincent Bourrier, Joanna K. Barstow, Mark S. Marley, Nikolay Nikolov, A. García Muñoz, Gilda E. Ballester, Tiffany Kataria, Nikole K. Lewis, Jorge Sanz-Forcada, Mercedes López-Morales, Kevin B. Stevenson, Gregory W. Henry, A. Lecavelier des Etangs, David Ehrenreich, Thomas M. Evans, and Heather A. Knutson
- Subjects
Earth and Planetary Astrophysics (astro-ph.EP) ,Physics ,010504 meteorology & atmospheric sciences ,James Webb Space Telescope ,Astrophysics::Instrumentation and Methods for Astrophysics ,FOS: Physical sciences ,Astronomy ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Parameter space ,01 natural sciences ,Exoplanet ,Panchromatic film ,Atmosphere ,Space and Planetary Science ,Planet ,0103 physical sciences ,Hot Jupiter ,Astrophysics::Earth and Planetary Astrophysics ,010303 astronomy & astrophysics ,Wide Field Camera 3 ,Astrophysics - Earth and Planetary Astrophysics ,0105 earth and related environmental sciences - Abstract
We present results from the first observations of the Hubble Space Telescope (HST) Panchromatic Comparative Exoplanet Treasury (PanCET) program for WASP-101b, a highly inflated hot Jupiter and one of the community targets proposed for the James Webb Space Telescope (JWST) Early Release Science (ERS) program. From a single HST Wide Field Camera 3 (WFC3) observation, we find that the near-infrared transmission spectrum of WASP-101b contains no significant H$_2$O absorption features and we rule out a clear atmosphere at 13{\sigma}. Therefore, WASP-101b is not an optimum target for a JWST ERS program aimed at observing strong molecular transmission features. We compare WASP-101b to the well studied and nearly identical hot Jupiter WASP-31b. These twin planets show similar temperature-pressure profiles and atmospheric features in the near-infrared. We suggest exoplanets in the same parameter space as WASP-101b and WASP-31b will also exhibit cloudy transmission spectral features. For future HST exoplanet studies, our analysis also suggests that a lower count limit needs to be exceeded per pixel on the detector in order to avoid unwanted instrumental systematics., Comment: 7 pages, 4 figures, 1 table, Accepted to ApJL
- Published
- 2017
40. VLT/FORS2 comparative transmission spectroscopy II: confirmation of a cloud-deck and Rayleigh scattering in WASP-31b, but no potassium?
- Author
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David K. Sing, Joanna K. Barstow, Thomas M. Evans, Neale P. Gibson, Nikolay Nikolov, Tiffany Kataria, and Paul Wilson
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010504 meteorology & atmospheric sciences ,FOS: Physical sciences ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,symbols.namesake ,0103 physical sciences ,Hot Jupiter ,Astrophysics::Solar and Stellar Astrophysics ,Rayleigh scattering ,010303 astronomy & astrophysics ,Spectrograph ,Space Telescope Imaging Spectrograph ,Astrophysics::Galaxy Astrophysics ,0105 earth and related environmental sciences ,Physics ,Earth and Planetary Astrophysics (astro-ph.EP) ,Very Large Telescope ,Astronomy ,Astronomy and Astrophysics ,Light curve ,Exoplanet ,Wavelength ,Space and Planetary Science ,astro-ph.EP ,symbols ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics - Earth and Planetary Astrophysics - Abstract
We present transmission spectroscopy of the hot-Jupiter WASP-31b using FORS2 on the VLT during two primary transits. The observations cover a wavelength range of $\approx$400-840nm. The light curves are corrupted by significant systematics, but these were to first order invariant with wavelength and could be removed using a common-mode correction derived from the white light curves. We reach a precision in the transit depth of $\approx$140 ppm in 15 nm bins, although the precision varies significantly over the wavelength range. Our FORS2 observations confirm the cloud-deck previously inferred using HST/STIS. We also re-analyse the HST/STIS data using a Gaussian process model, finding excellent agreement with earlier measurements. We reproduce the Rayleigh scattering signature at short wavelengths ($\lesssim$5300 $\AA$) and the cloud-deck at longer wavelengths. However, our FORS2 observations appear to rule out the large potassium feature previously detected using STIS, yet it is recovered from the HST/STIS data, although with reduced amplitude and significance ($\approx$2.5$\sigma$). The discrepancy between our results and the earlier STIS detection of potassium ($\approx$4.3$\sigma$) is either a result of telluric contamination of the ground-based observations, or an underestimate of the uncertainties for narrow-band features in HST/STIS when using linear basis models to account for the systematics. Our results further demonstrate the use of ground-based multi-object spectrographs for the study of exoplanet atmospheres, and highlight the need for caution in our interpretation of narrow-band features in low-resolution spectra of hot-Jupiters., Comment: 16 pages, 10 figures, 5 tables, accepted for publication in MNRAS
- Published
- 2017
- Full Text
- View/download PDF
41. The Complete transmission spectrum of WASP-39b with a precise water constraint
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Avi Mandell, Joanna K. Barstow, Benjamin Drummond, Hannah R. Wakeford, Tiffany Kataria, Nikole K. Lewis, Aarynn L. Carter, David K. Sing, Nikolay Nikolov, Gilda E. Ballester, Drake Deming, Tom J. Wilson, Thomas M. Evans, Heather A. Knutson, and Jayesh M. Goyal
- Subjects
Solar System ,010504 meteorology & atmospheric sciences ,Infrared ,Metallicity ,FOS: Physical sciences ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,7. Clean energy ,Atmosphere ,Planet ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,0105 earth and related environmental sciences ,Physics ,Earth and Planetary Astrophysics (astro-ph.EP) ,Astronomy and Astrophysics ,Exoplanet ,Amplitude ,13. Climate action ,Space and Planetary Science ,Astrophysics::Earth and Planetary Astrophysics ,Wide Field Camera 3 ,Astrophysics - Earth and Planetary Astrophysics - Abstract
WASP-39b is a hot Saturn-mass exoplanet with a predicted clear atmosphere based on observations in the optical and infrared. Here we complete the transmission spectrum of the atmosphere with observations in the near-infrared (NIR) over three water absorption features with the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) G102 (0.8-1.1 microns) and G141 (1.1-1.7 microns) spectroscopic grisms. We measure the predicted high amplitude H2O feature centered at 1.4 microns, and the smaller amplitude features at 0.95 and 1.2 microns, with a maximum water absorption amplitude of 2.4 planetary scale heights. We incorporate these new NIR measurements into previously published observational measurements to complete the transmission spectrum from 0.3-5 microns. From these observed water features, combined with features in the optical and IR, we retrieve a well constrained temperature Teq = 1030(+30,-20) K, and atmospheric metallicity 151 (+48,-46)x solar which is relatively high with respect to the currently established mass-metallicity trends. This new measurement in the Saturn-mass range hints at further diversity in the planet formation process relative to our solar system giants., Comment: Accepted for publication in AJ. 15 pages, 14 figures, 4 tables, 6 equations
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- 2017
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42. Variability in the Atmosphere of the Hot Giant Planet HAT-P-7 b
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James A. Blake, Nessa Fereshteh Saniee, Joanna K. Barstow, Ernst J. W. de Mooij, Hugh P. Osborn, and David J. Armstrong
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Earth and Planetary Astrophysics (astro-ph.EP) ,Physics ,Solar System ,Brightness ,010504 meteorology & atmospheric sciences ,Giant planet ,Brown dwarf ,FOS: Physical sciences ,Astronomy ,Astronomy and Astrophysics ,Phase curve ,01 natural sciences ,Wind speed ,Exoplanet ,13. Climate action ,Planet ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,010303 astronomy & astrophysics ,Physics::Atmospheric and Oceanic Physics ,0105 earth and related environmental sciences ,QB ,Astrophysics - Earth and Planetary Astrophysics - Abstract
As an exoplanet orbits its host star it reflects and emits light, forming a distinctive phase curve. By observing this light, we can study the atmosphere and surface of distant planets. The planets in our Solar System show a wide range of atmospheric phenomena, with stable wind patterns, changing storms, and evolving anomalies. Brown dwarfs also exhibit atmospheric variability. Such temporal variability in the atmosphere of a giant exoplanet has not to date been observed. HAT-P-7 b is an exoplanet with a known offset in the peak of its phase curve. Here we present variations in the peak offset ranging between -0.086+0.033-0.033 to 0.143+0.040-0.037 in phase, implying that the peak brightness repeatedly shifts from one side of the planet's substellar point to the other. The variability occurs on a timescale of tens to hundreds of days. These shifts in brightness are indicative of variability in the planet's atmosphere, and result from a changing balance of thermal emission and reflected flux from the planet's dayside. We suggest that variation in wind speed in the planetary atmosphere, leading to variable cloud coverage on the dayside and a changing energy balance, is capable of explaining the observed variation., Published in Nature Astronomy. 24 pages, including Supplementary Information. This is the accepted, but not journal-edited, version
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- 2016
43. Habitable worlds with JWST : transit spectroscopy of the TRAPPIST-1 system?
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Joanna K. Barstow and Patrick G. J. Irwin
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010504 meteorology & atmospheric sciences ,Kepler-69c ,FOS: Physical sciences ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Astrobiology ,Planet ,0103 physical sciences ,Transit (astronomy) ,010303 astronomy & astrophysics ,0105 earth and related environmental sciences ,Earth and Planetary Astrophysics (astro-ph.EP) ,Physics ,Planetary habitability ,James Webb Space Telescope ,Astrophysics::Instrumentation and Methods for Astrophysics ,Astronomy ,Astronomy and Astrophysics ,Habitability of orange dwarf systems ,13. Climate action ,Space and Planetary Science ,Astrophysics::Earth and Planetary Astrophysics ,Kepler-62e ,Circumstellar habitable zone ,Astrophysics - Earth and Planetary Astrophysics - Abstract
The recent discovery of three Earth-sized, potentially habitable planets around a nearby cool star, TRAPPIST-1, has provided three key targets for the upcoming James Webb Space Telescope (JWST). Depending on their atmospheric characteristics and precise orbit configurations, it is possible that any of the three planets may be in the liquid water habitable zone, meaning that they may be capable of supporting life. We find that present-day Earth levels of ozone, if present, would be detectable if JWST observes 60 transits for innermost planet 1b and 30 transits for 1c and 1d., 5 pages, 3 figures. Accepted as a letter in MNRAS. Typos corrected in this version
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- 2016
44. Dynamical theory driven west on CoRoT-2b
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Joanna K. Barstow
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010504 meteorology & atmospheric sciences ,Infrared ,Astronomy ,Astronomy and Astrophysics ,Phase curve ,01 natural sciences ,Exoplanet ,Physics::Space Physics ,0103 physical sciences ,Hotspot (geology) ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,Atmospheric dynamics ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,Geology ,0105 earth and related environmental sciences - Abstract
A peak in the infrared phase curve occurring after eclipse suggests a westward shift in the dayside hotspot of hot giant exoplanet CoRoT-2b, calling into question our understanding of atmospheric dynamics on hot gas giants.
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- 2018
45. VLT FORS2 comparative transmission spectroscopy: Detection of Na in the atmosphere of WASP-39b from the ground
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Paul Wilson, Neale P. Gibson, David K. Sing, Joanna K. Barstow, Jonathan J. Fortney, Tiffany Kataria, Thomas M. Evans, and Nikolay Nikolov
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010504 meteorology & atmospheric sciences ,FOS: Physical sciences ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astronomy & Astrophysics ,Atomic ,Physical Chemistry ,01 natural sciences ,photometric [techniques] ,Particle and Plasma Physics ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,Nuclear ,Spectroscopy ,Absorption (electromagnetic radiation) ,010303 astronomy & astrophysics ,Spectrograph ,individual [stars] ,Astrophysics::Galaxy Astrophysics ,0105 earth and related environmental sciences ,Earth and Planetary Astrophysics (astro-ph.EP) ,Physics ,Very Large Telescope ,Astrophysics::Instrumentation and Methods for Astrophysics ,Molecular ,Astronomy and Astrophysics ,atmospheres [planets and satellites] ,Light curve ,Exoplanet ,Wavelength ,Space and Planetary Science ,Magnitude (astronomy) ,individual (WASP-39) [stars] ,spectroscopic [techniques] ,Astrophysics::Earth and Planetary Astrophysics ,Astronomical and Space Sciences ,Physical Chemistry (incl. Structural) ,Astrophysics - Earth and Planetary Astrophysics - Abstract
We present transmission spectroscopy of the warm Saturn-mass exoplanet WASP-39b made with the Very Large Telescope (VLT) FOcal Reducer and Spectrograph (FORS2) across the wavelength range 411-810nm. The transit depth is measured with a typical precision of 240 parts per million (ppm) in wavelength bins of 10nm on a V = 12.1 magnitude star. We detect the sodium absorption feature (3.2-sigma) and find evidence for potassium. The ground-based transmission spectrum is consistent with Hubble Space Telescope (HST) optical spectroscopy, strengthening the interpretation of WASP-39b having a largely clear atmosphere. Our results demonstrate the great potential of the recently upgraded FORS2 spectrograph for optical transmission spectroscopy, obtaining HST-quality light curves from the ground., 11 pages, 5 figures, accepted for publication in ApJ
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- 2016
46. Exoplanets with JWST: degeneracy, systematics and how to avoid them
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Sarah Kendrew, Patrick G. J. Irwin, Joanna K. Barstow, and Suzanne Aigrain
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Physics ,010504 meteorology & atmospheric sciences ,Cloud cover ,James Webb Space Telescope ,Astrophysics::Instrumentation and Methods for Astrophysics ,Astronomy ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,01 natural sciences ,Exoplanet ,Stars ,Planet ,0103 physical sciences ,Radiative transfer ,Astrophysics::Earth and Planetary Astrophysics ,Transit (astronomy) ,010303 astronomy & astrophysics ,0105 earth and related environmental sciences ,Eclipse - Abstract
The high sensitivity and broad wavelength coverage of the James Webb Space Telescope will transform the field of exoplanet transit spectroscopy. Transit spectra are inferred from minute, wavelength-dependent variations in the depth of a transit or eclipse as the planet passes in front of or is obscured by its star, and the spectra contain information about the composition, structure and cloudiness of exoplanet atmospheres. Atmospheric retrieval is the preferred technique for extracting information from these spectra, but the process can be confused by astrophysical and instrumental systematic noise. We present results of retrieval tests based on synthetic, noisy JWST spectra, for clear and cloudy planets and active and inactive stars. We find that the ability to correct for stellar activity is likely to be a limiting factor for cloudy planets, as the effects of unocculted star spots may mimic the presence of a scattering slope due to clouds. We discuss the pros and cons of the available JWST instrument combinations for transit spectroscopy, and consider the effect of clouds and aerosols on the spectra. Aerosol high in a planet’s atmosphere obscures molecular absorption features in transmission, reducing the information content of spectra in wavelength regions where the cloud is optically thick. We discuss the usefulness of particular wavelength regions for identifying the presence of cloud, and suggest strategies for solving the highly-degenerate retrieval problem for these objects.
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- 2016
47. Exoplanet Transmission Spectroscopy using KMOS
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Niranjan Thatte, Joanna K. Barstow, Suzanne Aigrain, Thomas M. Evans, Hannu Parviainen, and Neale P. Gibson
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Earth and Planetary Astrophysics (astro-ph.EP) ,Physics ,Star formation ,Astrophysics::Instrumentation and Methods for Astrophysics ,FOS: Physical sciences ,Astronomy ,Astronomy and Astrophysics ,atmospheres [planets and satellites] ,Exoplanet ,Galaxy ,Spectral line ,photometric [techniques] ,Stars ,Integral field spectrograph ,Space and Planetary Science ,spectroscopic [techniques] ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics - Instrumentation and Methods for Astrophysics ,Instrumentation and Methods for Astrophysics (astro-ph.IM) ,Image resolution ,Spectrograph ,spectrographs [instrumentation] ,Astrophysics - Earth and Planetary Astrophysics - Abstract
KMOS (K-Band Multi Object Spectrograph) is a novel integral field spectrograph installed in the VLT's ANTU unit. The instrument offers an ability to observe 24 2.8"$\times$2.8" sub-fields positionable within a 7.2' patrol field, each sub-field producing a spectrum with a 14$\times$14-pixel spatial resolution. The main science drivers for KMOS are the study of galaxies, star formation, and molecular clouds, but its ability to simultaneously measure spectra of multiple stars makes KMOS an interesting instrument for exoplanet atmosphere characterization via transmission spectroscopy. We set to test whether transmission spectroscopy is practical with KMOS, and what are the conditions required to achieve the photometric precision needed, based on observations of a partial transit of WASP-19b, and full transits of GJ 1214b and HD 209458b. Our analysis uses the simultaneously observed comparison stars to reduce the effects from instrumental and atmospheric sources, and Gaussian processes to model the residual systematics. We show that KMOS can, in theory, deliver the photometric precision required for transmission spectroscopy. However, this is shown to require a) pre-imaging to ensure accurate centering and b) a very stable night with optimal observing conditions (seeing $\sim$0.8"). Combining these two factors with the need to observe several transits, each with a sufficient out-of-transit baseline (and with the fact that similar or better precision can be reached with telescopes and instruments with smaller pressure,) we conclude that transmission spectroscopy is not the optimal science case to take advantage of the abilities offered by KMOS and VLT., Comment: 11 pages, accepted to MNRAS
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- 2016
48. Constraining the atmosphere of GJ 1214b using an optimal estimation technique
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Joanna K. Barstow, Suzanne Aigrain, Patrick G. J. Irwin, Leigh N. Fletcher, Jae-Min Lee, University of Zurich, and Barstow, J K
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Earth and Planetary Astrophysics (astro-ph.EP) ,Physics ,Optimal estimation ,Gas giant ,530 Physics ,Cloud top ,FOS: Physical sciences ,Estimator ,Astronomy and Astrophysics ,Astrophysics ,Computational physics ,Trace gas ,Atmosphere ,1912 Space and Planetary Science ,Space and Planetary Science ,Planet ,Neptune ,10231 Institute for Computational Science ,3103 Astronomy and Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics - Instrumentation and Methods for Astrophysics ,Instrumentation and Methods for Astrophysics (astro-ph.IM) ,Physics::Atmospheric and Oceanic Physics ,Astrophysics - Earth and Planetary Astrophysics - Abstract
We explore cloudy, extended H2-He atmosphere scenarios for the warm super-Earth GJ 1214b using an optimal estimation retrieval technique. This planet, orbiting an M4.5 star only 13 pc from the Earth, is of particular interest because it lies between the Earth and Neptune in size and may be a member of a new class of planet that is neither terrestrial nor gas giant. Its relatively flat transmission spectrum has so far made atmospheric characterisation difficult. The NEMESIS algorithm (Irwin et al. 2008) is used to explore the degenerate model parameter space for a cloudy, H2-He-dominated atmosphere scenario. Optimal estimation is a data-led approach that allows solutions beyond the range permitted by ab initio equilibrium model atmosphere calculations, and as such prevents restriction from prior expectations. We show that optimal estimation retrieval is a powerful tool for this kind of study, and present an exploration of the degenerate atmospheric scenarios for GJ 1214b. Whilst we find a family of solutions that provide a very good fit to the data, the quality and coverage of these data are insufficient for us to more precisely determine the abundances of cloud and trace gases given an H2-He atmosphere, and we also cannot rule out the possibility of a high molecular weight atmosphere. Future ground- and space-based observations will provide the opportunity to confirm or rule out an extended H2-He atmosphere, but more precise constraints will be limited by intrinsic degeneracies in the retrieval problem, such as variations in cloud top pressure and temperature., 15 pages, 13 figures, 10 tables. Accepted for publication in MNRAS
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- 2016
49. The science of ARIEL (Atmospheric Remote-sensing Infrared Exoplanet Large-survey)
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Manuel Güdel, Ignasi Ribas, P. Malaguti, M. R. Zapatero-Osorio, L. Puig, Neil Bowles, Franck Selsis, Emanuele Pace, A. Coustenis, Michiel Min, Jean-Philippe Beaulieu, M. Rataj, G. S. Wright, Göran Pilbratt, William Taylor, Tom Ray, Paulina Wolkenberg, Ingo Waldmann, Matthew Joseph Griffin, V. Coudé du Foresto, Marco Rocchetto, Tiziano Zingales, François Forget, Joanna K. Barstow, Olivia Venot, T. Encrenaz, Diego Turrini, Jérémy Leconte, Bart Vandenbussche, Paul Hartogh, P. O. Lagage, Giuseppina Micela, A. Heske, Marc Ollivier, Pierre Drossart, Enzo Pascale, M. Friswell, A. Moneti, Subhajit Sarkar, Giovanna Tinetti, Jonathan Tennyson, Juan Carlos Morales, Paul Eccleston, Leen Decin, University College of London [London] (UCL), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, ECLIPSE 2016, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astronomico di Palermo (OAPa), Istituto Nazionale di Astrofisica (INAF), Institut de Génomique Fonctionnelle de Lyon (IGFL), École normale supérieure de Lyon (ENS de Lyon)-Institut National de la Recherche Agronomique (INRA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA), University of Valencia, Space Research Centre of Polish Academy of Sciences (CBK), Polska Akademia Nauk = Polish Academy of Sciences (PAN), Institut d'Astrophysique de Paris (IAP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institute for Astronomy [Vienna], University of Vienna [Vienna], Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Amsterdam [Amsterdam] (UvA), Dpto. de Organización de Empresas, Escuela Técnica Superior de Ingeniería Industrial de Barcelona, Universitat Politècnica de Catalunya [Barcelona] (UPC), Department of Physics and Astronomy [Leicester], University of Leicester, Department of Atmospheric, Oceanic and Planetary Physics [Oxford] (AOPP), University of Oxford, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), College of Engineering, Swansea Univ, School of Physics and Astronomy [Cardiff], Cardiff University, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Università degli studi di Verona = University of Verona (UNIVR), Department of Physics and Astronomy [UCL London], Catholic University of Leuven - Katholieke Universiteit Leuven (KU Leuven), McMaster University [Hamilton, Ontario], Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Max Planck Institute for Solar System Research (MPS), École normale supérieure - Lyon (ENS Lyon)-Institut National de la Recherche Agronomique (INRA)-Université Claude Bernard Lyon 1 (UCBL), European Space Agency (ESA), Polska Akademia Nauk (PAN), University of Oxford [Oxford], École normale supérieure - Paris (ENS Paris)-École normale supérieure - Paris (ENS Paris), Università degli Studi di Verona, University College of London [London] ( UCL ), Laboratoire d'études spatiales et d'instrumentation en astrophysique ( LESIA ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire de Paris-Université Paris Diderot - Paris 7 ( UPD7 ) -Centre National de la Recherche Scientifique ( CNRS ), Max Planck Institute for Solar System Research ( MPS ), Laboratoire d'Astrophysique de Bordeaux [Pessac] ( LAB ), Université de Bordeaux ( UB ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Bordeaux ( UB ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), INAF - Osservatorio Astronomico di Palermo ( OAPa ), Istituto Nazionale di Astrofisica ( INAF ), Institut de Génomique Fonctionnelle de Lyon ( IGFL ), École normale supérieure - Lyon ( ENS Lyon ) -Institut National de la Recherche Agronomique ( INRA ) -Université Claude Bernard Lyon 1 ( UCBL ), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique ( CNRS ), European Space Research and Technology Centre ( ESTEC ), European Space Agency ( ESA ), Space Research Centre [Warsaw] ( CBK ), Polska Akademia Nauk ( PAN ), Institut d'Astrophysique de Paris ( IAP ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Astronomical Institute Anton Pannekoek ( AI PANNEKOEK ), University of Amsterdam [Amsterdam] ( UvA ), Universidad Politécnica de Cataluña, Department of Atmospheric, Oceanic and Planetary Physics [Oxford] ( AOPP ), Laboratoire de Météorologie Dynamique (UMR 8539) ( LMD ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -École polytechnique ( X ) -École des Ponts ParisTech ( ENPC ) -Centre National de la Recherche Scientifique ( CNRS ) -Département des Géosciences - ENS Paris, École normale supérieure - Paris ( ENS Paris ) -École normale supérieure - Paris ( ENS Paris ), School of Physics & Astronomy [Cardiff], Institut de Recherches sur les lois Fondamentales de l'Univers ( IRFU ), Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay, K.U.Leuven, Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA)-École normale supérieure - Lyon (ENS Lyon), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), and University of Verona (UNIVR)
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[SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP] ,Orbital mechanics ,Stellar classification ,7. Clean energy ,01 natural sciences ,Space missions ,Space exploration ,Astrobiology ,law.invention ,010309 optics ,Telescope ,law ,Planet ,0103 physical sciences ,Electronic ,Atmospheric science ,Exoplanets ,IR spectroscopy ,Electronic, Optical and Magnetic Materials ,Condensed Matter Physics ,Computer Science Applications1707 Computer Vision and Pattern Recognition ,Applied Mathematics ,Electrical and Electronic Engineering ,Optical and Magnetic Materials ,010303 astronomy & astrophysics ,Physics ,space missions ,atmospheric science ,Astrophysics::Instrumentation and Methods for Astrophysics ,Astronomy ,Planetary system ,[ SDU.ASTR.EP ] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP] ,Exoplanet ,13. Climate action ,Terrestrial planet ,Astrophysics::Earth and Planetary Astrophysics - Abstract
International audience; The Atmospheric Remote-Sensing Infrared Exoplanet Large-survey (ARIEL) is one of the three candidate missions selected by the European Space Agency (ESA) for its next medium-class science mission due for launch in 2026. The goal of the ARIEL mission is to investigate the atmospheres of several hundred planets orbiting distant stars in order to address the fundamental questions on how planetary systems form and evolve. During its four (with a potential extension to six) years mission ARIEL will observe 500+ exoplanets in the visible and the infrared with its meter-class telescope in L2. ARIEL targets will include gaseous and rocky planets down to the Earth-size around different types of stars. The main focus of the mission will be on hot and warm planets orbiting close to their star, as they represent a natural laboratory in which to study the chemistry and formation of exoplanets. The ARIEL mission concept has been developed by a consortium of more than 50 institutes from 12 countries, which include UK, France, Italy, Germany, the Netherlands, Poland, Spain, Belgium, Austria, Denmark, Ireland and Portugal. The analysis of the ARIEL spectra and photometric data in the 0.5-7.8 micron range will allow to extract the chemical fingerprints of gases and condensates in the planets' atmospheres, including the elemental composition for the most favorable targets. It will also enable the study of thermal and scattering properties of the atmosphere as the planet orbit around the star. ARIEL will have an open data policy, enabling rapid access by the general community to the high-quality exoplanet spectra that the core survey will deliver.
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- 2016
50. Reanalysis of Uranus' cloud scattering properties from IRTF/SpeX observations using a self-consistent scattering cloud retrieval scheme
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D. Tice, Nicholas A Teanby, Leigh N. Fletcher, Joanna K. Barstow, G. S. Orton, Gary R. Davis, and Patrick G. J. Irwin
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Physics ,Earth and Planetary Astrophysics (astro-ph.EP) ,Atmospheres, composition ,Scattering ,Extinction (astronomy) ,Uranus ,Astronomy ,FOS: Physical sciences ,Astronomy and Astrophysics ,Overtone band ,Data reduction techniques ,Spectral line ,Uranus, atmosphere ,Physics - Atmospheric and Oceanic Physics ,Space and Planetary Science ,Atmospheric and Oceanic Physics (physics.ao-ph) ,Radiance ,Astrophysics::Earth and Planetary Astrophysics ,Atmospheres, structure ,Stratosphere ,Astrophysics::Galaxy Astrophysics ,Line (formation) ,Astrophysics - Earth and Planetary Astrophysics - Abstract
We have developed a new retrieval approach to modelling near-infrared spectra of Uranus that represents a significant improvement over previous modelling methods. We reanalysed IRTF/SpeX observations of Uranus observed in 2009 covering the wavelength range 0.8 to 1.8 microns and reported by Tice et al. (2013). By retrieving the imaginary refractive index spectra of cloud particles we are able to consistently define the real part of the refractive index spectra, through a Kramers-Kronig analysis, and thus determine self-consistent extinction cross-section, single-scattering and phase-function spectra for the clouds and hazes in Uranus' atmosphere. We tested two different cloud-modelling schemes used in conjunction with the temperature/methane profile of Baines et al. (1995), a reanalysis of the Voyager-2 radio-occultation observations performed by Sromovsky, Fry and Tomasko (2011), and a recent determination from Spitzer (Orton et al., 2014). We find that both cloud-modelling schemes represent the observed centre-of-disc spectrum of Uranus well, and both require similar cloud scattering properties of the main cloud residing at approximately 2 bars. However, a modified version of the Sromovsky, Fry and Tomasko (2011) model, with revised spectral properties of the lowest cloud layer, fits slightly better at shorter wavelengths and is more consistent with the expected vertical position of Uranus' methane cloud. We find that the bulk of the reflected radiance from Uranus arises from a thick cloud at approximately the 2 bar level, composed of particles that are significantly more absorbing at wavelengths > 1.0 micron than they are at wavelengths < 1.0 micron. This spectral information provides a possible constraint on the identity of the main particle type., 52 Pages, 14 Figures
- Published
- 2016
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